Wow ok so.....gotta do my homework and make sure I'm using oem. So ill start with the seafoam, oil change, spark plugs wires, than diffs, transfer case change, and than new rad with cooler and i should be on thw right path. Should i have thw tranny fluid changed?
If it's nice and red and doesn't smell burnt, the tranny fluid is probably ok. But, since it's a new-to-you truck, if you don't know when it was last changed and/or if the filter has ever been changed, you might want to do that. If the fluid looks no bueno, but the tranny seems to operate correctly and smoothly, I'd consider dropping the pan, changing the filter, and also flushing it. So your options are (depending on the fluid condition)..
1) Just pull the drain plug on the tranny and fill it back up (you fill it through the dipstick). There is some discrepancy as to how much fluid to put back in when you do this. The manual says about 2 qts, but it seems that most of us get 4-5 quarts out. Mine drained almost 5 qts and it read full at hot temp on the dipstick (after taking it for a 20 mile drive and checking it in P w/ the engine running). It's best to make sure it's at the correct level before you start doing anything, and then measure what drains out and replace with the same amount.
2) Do #1 above in addition to dropping the pan and replacing the filter. I got about 6 or 7 quarts out total when I did this. It's a messy job though and no fun at all.. especially when ATF is dripping in your nose and mouth when you're under there scraping the old gasket off the tranny.
3) Do #1 and #2 above in addition to flushing it with the tranny's own pump. This DIY method works great and the write up will also answer just about everything concerning tranny maintenance..
Dropping Pan And Flushing Transmission
It took me about 16 qts of ATF to do the complete "#3".
4) Pay a shop to drop the pan and change the filter and/or flush it.