nv5600 install
 

has anybody put a nv5600 in an old 12V? if you have did you need an adapter or anything to make it work or is it just a bolt in deal?

I've gone that transmission in mine. It bolts right in. However, you'll have some driveline changes. You'll also need a different starter.

shorter driveshaft? and do you know which type of starter?

u need the starter that came off whatever year truck the 5600 is coming out of

You will need the adapter plate and starter off the donor

What transmission do you have in your truck right now? Whether it has to be shortened or lengthened will depend on what you have in there right now. Keep in mind, you'll need the
flywheel housing (the factory adapter between the engine and bellhousing), clutch release components, and you'll need to make some cross member fabrication, floor modifications, and some exhaust rerouting to get it to work.

its just got the factory getrag in there now. its alright but the previous owner said he's had trouble with it when towing and since i typically pull a horse trailer i dont wanna risk it.

That would definitely mean having to lengthen the rear driveline to accommodate an NV5600. That said, the factory Getrag should be just fine for pulling a horse trailer. Just keep the oil level overfilled and don't lug it in 5th gear. The NV5600 is an excellent transmission but it's expensive and parts are hard to come by.