[old Rusty C10]

it also depends on the type of the rebuild kit the rebuilder used. Anytime ive gone to one of those mom and pop shops and theyve used the cheapest parts they could find ,i kill the tranny in about a year. Lately ive found a rebuilder who uses the factory rebuild kits( at least thats what im told) that are made by the factory for the truck itself, and ive had no problems, and i beat the hell outta my truck hauling waaay too much weight for waaay to long a distance.
If youre guilty of beating the hell outta your truck first off you should install a tranny cooler to make sure that the heat is disappated as heat is what kills the fluid and then the tranny.
If your truck aint going into gear first off check the fluid level and the fluid color. If thats good then go under and check the linkage with both the emergency brake on and someone in the truck stamping on the brake pedal. if both of those check out ok, and the electrical wires are properly hooked up its time for a tranny
good luck