First, thank you fellow Z clubbers for all the responces for my electrical question. Now for one more. My Z I am getting ready to start on has a production date of 10/70 and I'm slowly learning all the little differences between this early Z and all the other Z's I've had in the past, 72 and 73's. I've read a couple of different posts about how the early Z's diff was a little more forward, resulting in more rear end clunk, and quickly worn out u-joints, so they fixed it by moving the diff back a little. Is that correct? Does anyone know when they moved the differential back to fix this problem?

I would like to put a 5-speed in mine and keep the original R-180, but before I start, I would like to know what are my best options so I can avoid these problems, or do I have to live with it?

Thank you for your time.

The rear end was moved rearward about 35 mm with the introduction of the Type B transmission for the 72 Model Year. That would have been around 09/71. Along with that rearward move - a longer drive shaft was used and the rear transverse link {lower link below the rear of the differential} was changed from being straight to curved.

Your biggest problem will be with the difference in the position of the shifters - between your Type A 4 spd. and the Type B 5 spd you most likely want to install. The hole in your transmission tunnel is located about 2" farther rearward, than the hole in the transmission tunnels on the 72/73 240Z's.

So you either have to modify the hole in your transmission tunnel - by cutting some of the metal out of the front of the hole - or you have to have a modified shifter such that the shift lever comes up though the transmission tunnel farther rearward.

See: http://www.zhome.com/ZCMnL/tech/AandBtranny.htm

FWIW,

Carl B.

Edited April 19, 201212 yr by Carl Beck

To fix the angular problem, you'll need to get a 72 diff hanger (curved not straight), a longer driveshaft from a 72, flip your mustache bar, and install a 72 front diff mount (or flip the one you've got 180 degrees).

Moving the diff back was done primarily to reduce noise and vibration. There isn't a u-joint or halfshaft reliability issue with the diff in the forward position.