You can change cruising speed with a different differential.

 

On that topic though, be aware that 1975 has an odd bolt pattern on the differential.  So if you do swap differentials, you'll need to get a 76-78 propeller shaft (center driveshaft).  Or swap pinion flanges.

 

On the wheels - it's tire diameter that matters.  A "normal" 14 wheel can have the same diameter as a 16" wheel with a low profile tire.  http://www.discounttire.com/dtcs/infoTireMath.do

 

On transmissions - many people focus on cruise but they should really focus on 1st gear.  

Edited November 2, 201510 yr by Zed Head

Zed, good point on the tire diameter. Thanks

Mud,

Thanks, that link didn't work, what's the name of the book, I'll get it ASAP. I'm on the hunt for an 5 speed. I think part of the reason I'm looking at a 5 speed, the car I bought has 14" wheels, maybe it would be a more comfortable RPM at cruising speed with some 16" wheels, right? I think I'll buy the rims, tires first, then see how comfortable the cruising speed is. Sound good everyone

Try this link: http://www.amazon.com/Rebuild-Your-Nissan-Datsun-Engine/dp/1931128030/ref=sr_1_1?ie=UTF8&qid=1446502999&sr=8-1&keywords=how+to+rebuild+your+nissan+ohc

Thanks, it's ordered, excellent.

Troy

Troy,

Just to confirm what was stated here-in the help you can get here is far and away the best you can find anywhere on the web.