I have a rebuilt 350 engine nothing special and a rebuilt TH350 transmission to install on my project truck. I have two rear end axles, one has 3.73 gears (non posi) and the other 3.08 gears. I intend on using the 3.08 gear axle due to the fact that it is a 5 lug axle and the other axle is a 6 lug. QUESTION: Which would you choose to install with this application and why?
Just an RPM comparison that might help you decide: With the 3.08 rear, your engine will turn approx 2590 rpm @ 70 mph using a 28" tall tire. With the 3.73 rear, your engine will turn approx 3130 rpm @ 70 mph using a 28" tall tire. The 3.73 will give you better acceleration but you may find the higher rpm at highway speeds annoying, depending on your exhaust. I had a 4.11 in my '57 and the engine/exhaust noise drove me nuts. I swapped in a 2.73 and it's really nice on the highway but not nearly as quick accelerating. I think I'd like about a 3.42. JMO.
If you are going to haul/work the truck, then use the 373, if you are just going to drive it as a car, the lower would be good for the highway. If you are going to trailer it to shows, . .. ? I had a 514 in by truck and changed that to a 410, then had a 342 built and now wish I had gone with a 373 or 380 something. But going down the highway is so nice, 70 v/s 45. In town I have to stay in the lower tranny gears, the granny gear speed I have now is close to what my old second was.
I have a 350/350 in my '70 C-10. It has the 3.08 posi gears and I've driven it between Phoenix and Calif. (350 miles), pulling a loaded trailer, numerous times. I haven't noticed a problem with acceleration, in fact it will chirp the tires shifting to 2nd if I have my foot in it! I'd highly recommend the 3.08's for your application. If you go with the other gears, 5 lug axels are available. Good Luck.
If you have 5 lug for the front, use the 5 lug, if you want the lower gears have the axles changed to 5 lug. You can call Hoopers Rear End Exchange in Sun Valley, Ca and talk to Anthony. 1.818.899.0952
Thanks for all the input from all you guys, I have decided to install the 3.08 axle rear end, It seems to be the best fit for my cruising application, and I can alway swap them around again in the future if need be. Thanks again!
