looking at buying a 91 k5 that has 193,000 miles on it and to my knowledge has never had a motor/trans rebuild done. everything feels tight strong and there is virtually rust free. But the transmission fluid is brown, it doesnt smell burnt but definatly does not look right. there was no whining from the transmission that i could tell untill i got on it and when the motor wound out in 2nd gear there was a bit of whining (could have just been gear noise). Everything felt great though it shifted just right and in the right place very little slop. Any advice change the fluid leave it? i put 100$ deposit down on the truck so if i walk i lose it. this is 1 of 2 k-5's in my area for 2000 or under. the other one is in way worse shape. any advice cheap ways to get a new/rebuilt 700r4 to swap if it goes? any information would be greatly appreciated.