Thanks for the info,50-3600-guy.

I've got a similar problem in that I have an 81 C3 Vette TH350C and driveshaft. Obviously that will require lengthening!
The problem I have is I'm using an 86 Firebird (Borg Warner) rear axle and have discovered the UJ sizes are different too.
I ordered a 'crossover' UJ from Speedway and it doesn't fit!
Can you (or anyone else for that matter) tell me what UJ I actually need?

1950 Chevy Advance Design 3100 in Scotland
In the Stovebolt Gallery
More pix on Flickr.
I've definately got this truck thing in my blood ... my DNA sequence has torque settings
"Of all the small nations of this earth,perhaps only the ancient Greeks surpass the Scots in their contribution to mankind" Winston Churchill.