I'm trying to make my 1st gen Firebird a little more highway friendly. My '67 has the Saginaw 4 speed with 3.55 rear gears and I'm running the tallest tires I can squeeze under it (275/60 x 15) but the engine is still turning almost 3500 rpms at 60 mph. I know I have options for making this car easier to deal with on long trips without killing my performance but they're all so damned expensive! Here's the options I've come up with and their pros and cons.

Tremec 5 or 6 speed conversion. This seems like THE best option for lowering my highway rpms (and keeping my tire smoking abilities) and for a mere $3600 (which, by the way, is more than I have in the ENTIRE car) I could make this happen. My budget says this is the worst idea imaginable. I could cut the cost if I could find a TKO 500 or 600 used but so far I haven't had any luck.

Gear Vendor overdrive. This is the one I'd go with if I had a Muncie trans instead of the Saginaw and virtually limitless funds. I could keep all the grunt, and with the press of a button, lower my highway cruising rpms considerably. Unfortunately, it's almost as expensive as the 5 speed conversion.

Doug Nash 5 speed swap. Still pretty damned expensive and I'd have to change my 3.55s for something closer to 2.76s which, correct me if I'm wrong, requires a different carrier than what I currently have. This plan would really only work if I could find an old trans that I could pick up much cheaper than a new one.

Last, and cheapest, is just swapping out my rear gears but that compromises everything.

Does anyone out there have a better option or am I just too damned broke to have the best of both worlds?

Thanks for taking the time to read this and (hopefully) giving me a better solution.

There's no cheap way around that extra gear for manual or automatic. They got us by the nuts and they know it. This is why I stick with my 3.73's and just let it sing.

Yeah Bigchief, I'll probably do that before I just change the gears. I just can't stomach the idea of losing my "on demand" smoke screen.

I found something about swapping out the tail housing of a Saginaw 4 spd with the tail housing from a 3 spd (with overdrive) Saginaw. Maybe I can pick up a 3 spd cheap...if I can even find one. Does anyone have any info on that?

Is there any way of changing the gears in your transmission? I don't know about the Saginaw, but I seem to remember someone with Munci gears that would give you a wider ratio 1st, second and third with an overdrive fourth.

I went with the TKO 600 but now that my house needs a new roof I wish I saved the money and just changed out the 373 rear.

I remember reading about an overdrive gearset for a muncie 4 speed but I imagine that is not cheap either since you have to change the cluster and all the gears.

Bluebird, I did some checking on that & I can change 1st through 3rd on a Saginaw but I couldn't find anything to modify 4th. I'm hearing from a lot of sources that the "Sag" is too weak to even mess with & I should ditch it for a Muncie. Muncies aren't cheap though & just swapping trannys isn't gonna help me...unless...(this brings me to bigchiefs reply) I find out I can change final drive gears in a Muncie. I'll do some research on that. Thanks guys for the alternatives.

Mccloed has a new overdrive 5 speed that supposedly is a direct swap with no tunnel cutting or any other parts needed.

http://www.mcleodracing.com/index.php/dr...ar-5-speed.html

I was just reading about the Muncie overdrive thing the other day. It didn't sound like a good idea. Give you the same first gear ratio as the M21 and it's quite a stretch to 2nd gear. Third is 1:1 and 4 th is like .89. Might be ok in the perfectly thought out setup but it's going to be a dog in most circumstances. Probably end up so disappointing you would end up the car. Just wouldn't be any fun anymore.

Bob S. That's an awesome find! I've been researching this for a week & somehow that never came up. Sounds like it would save me about a $1000 over the other 5 speed conversions & the auxiliary overdrive. I'm too broke to swing it right now but it's on the top of my list.

Firebob I think you're right. Plus I'd have to buy a Muncie first. I imagine the final cost would be way up there, especially if I still had to change my rear gears. That puts me in the same boat as switching over to a Doug Nash 5 speed. The Muncie would probably be stronger.

I sold my Muncie for $850, if you had to pay that and another $400 or so for the gears you're starting to get up there in $. Will the Muncie fit on the same bellhousing?

I've been trying to encourage somebody here to try the Mcleod trans to see how it works out before I take the plunge

BB428, if I could get into that setup @ under $1500 I'd be soooo happy. Haha. I think the bell-housings are the same (I've never compared them) but it doesn't matter because I have a bell-housing that I know came off of a Muncie. At least I have some small part of this puzzle already.

Bob S. I'd be more than happy to be the Guinea pig on that if I could swing the cost. It sounds like the best option for me. If I can sell off a kidney, lung or testicle I'll "take the plunge" & let you know all the details. How much hp/torque are you making?

Just a 65 389 with an 068 cam. I've got 323 gears. The steeper 1st and the overdrive 5th should make driving much more fun. And not needing to cut the tunnel, shorten the driveshaft, and get a custom cross member is the advantage over a tremec.

Hmmm, I may need a kidney, I wonder what the shipping would cost?

Very cool Bob S.
Mine is a '64 389 bored .40 over with the same cam. I'm running the 3.55s.
I totally agree.

Well BB428 I've got an ice chest & some dry ice. If you still had that Muncie I'd trade you straight across, although after you saw the condition of this worn out 42 year old kidney you'd probably want a few hundred bucks. HAHAHA!

Summit sells the Mcloed trans. I talked to them and it looks like you can order one and pick it up at the Talmadge, OH store. You have to have it set up with the right shifter config to fit in the console. If/when I pull the trigger, I'll do this. I'm often in OH on business.

If the McLeod is anything like the tKo 5 speed you will have to cut the shifter hole longer at the back to fit the shifter. Console would have to be moved back as well to clear the shifter.

That would be 22 years younger than the ones in my body, I could get two more decades of swilling beer at skydiving meets and fishing trips.

The shifter on the Tremec can be mounted in eight different positions to fit most tunnels without having to cut. Mine ended up in the same position as the Muncie, I don't have a console though.

Bob S.
I haven't been to Ohio in a few years and I don't plan on going there any time soon. HAHA! Do they have a store closer to Oklahoma?

Big chief
All the advertisements say there's no tunnel modification necessary but I figured there would be something that would need "trimming". I don't have a console and I already need new carpet so I'm not too worried about it. I need a shift lever that kicks back so I don't have to lean forward when I shift into 3rd.

BB428
My kidneys are afraid of heights so they wouldn't really work for you. (Not really...I'm just weaseling my way out of our deal because I want to swill a lot more beer in the next 20 years. Do you need a testicle instead? I don't plan on using mine...EVER! HAHA) P.S. That shifter looks like it's in the perfect position.

No, don't need any other organs, ankle, knees and wrists would help.
The shifter is just left of center and unless I have the seat tilted too far back I can reach fifth without moving my shoulder. I have a console I traded for a hood, I was going to repair/rebuild it and install it in my car but I like the look of the shifter coming out of the carpet. Just me.

It looks good that way. I'm not putting a console in mine either.
Aside from the cost & the fact that you need a new roof (ugh) how happy are you with the Tremec? Would you do it all over or would you really just change rear gears?

I really like it, shifts nice and the overdrive is great. There is another with an overdrive somewhere around 0.83:1, would be good for road racing or two lanes. But mine is somewhere around 0.65, really drops the rpm. I built my engine with that in mind, going for more low rpm torque than high rpm horsepower. But it cost me a pile of money, I thought I could afford it at the time but in hindsight,,,
Yeah I'd do it over, what the heck.

I'd get the .65 also. I'm planning on doing the Hot Rod Power Tour this year & I'd rather get more than 9 mpg. If I can get 15 or 20 then the fuel savings alone will pay for part of the conversion. I'd love to do the Tremec swap but I'm afraid I wouldn't be able to afford to go on the Power Tour afterwards. Plus, similar to your new roof problem, I need a new heat & air system for my house. I guess if I spend all my time in the garage then I really don't need heat/AC, huh? Haha