I decided to post my results of the conversion to a 200-4R 4 speed overdrive tranny. The reason for the conversion can be followed in this topic:

/forums/ultimatebb.php?ubb=get_topic;f=23;t=001778

Here are the problems I ran into with the conversion:

Problem #1 The back of the tranny pan was resting on the crossmember
Solution: Install 1/2" spacer between crossmember and tranny mount.

Problem #2 Because of the spacer the engine was slightly tilted forward and the driver side header was hitting the lower motor mount bolts.
Solution: Took the top of the bolt (thread end) off with a Sawzall.

Problem #3 The aftermarket exhaust from the headers back didn't line up with the header collectors.
Solution: Big hammer

What I like about this conversion:

1st gear is amazing. I'm running a 3.08 posi rear and with the 2 spd it was a dog out of the hole. Now I can light up the tires. The spacing of the gearing is perfect. At 55 MPH in OD the engine is at 1200 RPM! I find myself locking out OD below 60 MPH because the RPMs are so low. When you hit the accelerator in downshifts clean, fast and puts you in the correct gear for the speed/RPM. The only drawback I see is that it emphasizes how bad the old suspension pieces on the Bird are. You can feel the leafs twisting slightly when the power hits the rear (never felt that before!). I would highly recommend this swap for anyone running the automatic 2 speed in their Firebird.

G.J.
68 350 Coupe

How much did it cost you to do the complete conversion?

Almost $2000....all those extra parts added up. Here is the parts breakdown:

Level 2 Tranny $1020:

http://www.2004r.com/trans/level2.shtml

Shipping $185 (to my house)
Converter $154
Inspection cover $25
Dipstick $30
TV system for Demon carb $120
Converter lockup kit $28
Tranny lines $129
Matched speedo gears $44
TH400 crossmember $145
Installer kit $67
Shifter conversion kit for OD $85
New shift cable $55

Okay, maybe $2085!

G.J.
68 350 Coupe

what made you use the 200-r4 instead of the 700-r4

i chose the 200 for ease of installation over the 700.

i used the tall mount instead of adding spacers.

i've got about ~$1000 in mine, rebuilt with a shift kit... i still need to hook up the lockup function, but i just need to find a plug. then i will get a brake switch and vacuum switch. probably about ~$35 in parts/wires. i could just use a manual switch.

Adds up fast.

I know at least three people that went with the 700R4 in their Chevys. They all complained that the gearing really drops the rpms during the 1 -2 shift.

And if you're running an engine with a lot of low speed torque and anything above 3.55 rearend, the first gear is useless. Not only do you incinerate the tires, but if your redline is less than 6000 rpm, you're shifting into 2nd just out of the hole.

Either tranny is going to set you back alot just to make it last behind a 400 or 455.

the 200 has a less drastic 1-2 shift than the 700. mine is starting off in 2nd though. with my rearend choice it is still lower than OE was with the st-300. i think i can tweak it to start out in first so i can incinerate my tires with my 6cy