I was looking at the universal joints from napa and saw they have several to choose from. The super strength list as a 1 1/16" O.D. Bearings while the Proformer U Joint don't specify the size.

Can someone recommend the front and back Ujoints to use.

Napa Link

looks like they're all 1 1/16 OD, so it's just a matter of preference. i like spicer or moog

here's a link to moog.

http://www.rockauto.com/catalog/moreinfo.php?pk=387690&cc=1249231

+1 for Spicer. Heard nothing but praise for them.

Everything I have read, solid u-joints are stronger than the greaseable type...fwiw.

Thought I would wake up this old thread as I have been studying u-joints available to replace mine on the factory original drive shaft. (the U-joints were replaced once in 1970)

What has me confused is the 1 1/16" OD cap size mentioned above verses the 3R type. The best I can tell, the Spicer 3R and most vehicle fit charts for '67-69 Firebirds show a 1 1/8" (1.125) cap OD. What should be the correct size?

I have not yet lifted the car to try to measure what's on the car (assuming enough of the assembled cap is exposed to measure.

Whether I choose greaseable or not, I have not decided yet.

If greaseable; the specs on the AMES Part #: FR830 and Spicer 5-3147X 3R Series U-joint Greaseable are the same:
3.625 inches wide in both directions
All 4 bearing caps are 1.125 inch diameter with inside "C" Clips to lock the cap in place.
The span between the yoke inner surfaces where the "C" Clips lock in is 2.556 inches

The 5-795X Dana Spicer 3R Series appears to be a possibe Non Greasable one.

Are those the correct sizes for a '68?

seems to be a difference in U joints depending if the car is a 4 speed car or an automatic.
Supposedly the 1.0625 U Joint is for stick shift cars and the 1.125" is for automatic.
But in all reality you need to take the shaft out and measure to see exactly what you have,

is excellent advice.

I got under my '68 and measured the rear u-joint which is the drive shaft end I had the most questions. If I didn't measure the existing part, there was little chance of getting the correct u-joint if I relied on most of the parts vendosr charts.

1. Having studied the Spicer catalog entries for 1st Gens, I find it recommends the wrong rear u-joint. Having an original TH400 & yoke, drive shaft, and diff; I can say the Spicer recommendation would not work on mine or likely other factory originals. Spicer shows each axis has a different cap diameter (1 1/16 for differential, 1/1/8 for drive shaft. Mine has the 1 1/8 for all four caps and I know for sure my diff yoke is original. It's not precise trying to measure the caps while on the car and laying under it but in multiple measurements I got 1.118, 1.127 and 1.126, 1.127, 1.124 for the diff caps and drive shaft caps respectively.

2. For anyone with a 1st gen with different/unknown drive train, measuring is essential.

Interestingly, I discovered that the u-joints with external clips are measured differently then the internal clip type (like mine). For each axis I assumed incorrectly it was end of cap to end of cap. It's clip to clip so only the external clip type are really end to end.

As my old '72 parts book shows, 7806140 fit front and rear of all Pontiacs from '64-69. So, I'm not sure why the Spicer catalog shows different front and rear and hydromatic and manual.

Note that AMES offers just one u-joint (FR830), a greaseable for all 1st gens, which now makes sense.