What rear axle did the factory put under the 78 ??? Would you regear the factory rear end or swap in something else ?? Future plans include a 700r4 and 3.73 gears. What would you recomend for the rear axle ??

Your truck came with a 7.5 inch rear gear and if you are not going to be putting slick on and beating on it it should be fine. The 3.73 gears and posi are a good combination with the th700r4.........Dan

funny you should ask...i have a 78 and just had an eaton posi unit with 3.73's put in. i also have the 700r4 and the combo is unbelievable, well worth the money. the rear end was a 7.5 inch 26 spline with 2.41's(yuck)!! great takeoff power now and it runs about 2000 rpm doing 65 to 70 mph so its not horrible on gas. i'd also like to suggest a B&M slapshifter to go with that tranny, it makes the driving experience a lot of fun. good luck.

where could i get that eaton posi unit with 3 73 gears?

i have a th350 and i would also like to get the slapstick shifter...before i get my t56 6-speed

u guys dead?

If you are very mechanically inclined you could install your own posi differential, but i would recommend going to your local drive train specialists and having them put in your differential. You can also purchase differentials on summit or jegs and even ebay. Just make sure that the axels and the diffential have the same number of splines.