Transmission problem!

[joeyjarvis23]

Ok so I purchased a 97 F250 HD with 200,000 Miles I just installed a new ford tranny with the upgrads.. I also installed cold air intake exhaust and a ts chip with php programming.. the truck has 35's and 3.55 gears, The truck runs amazing empty but soon as i try to pull my fifth wheel 9000lbs. it tries to shift constatenly. if feels like the torque converter locks and unlock all the time..and it tries to run in that spot were its building high egts but doesnt seam to have any power then it shifts lower and immediatly shifts back.. I m thinking i should put 4.56 Gears but im not sure please help! by the way the truck does not have the tq problems on stock i never feel it do anything. just gutless like the gears are too far apart>

[Mutley]

Could be those 3.55's. I drag a 30' tt around with 4.11's (albeit with a 5 spd) and feel no loss of energy. I was lusting after 3.55's for a while now but I think you may have convinced me to stick with what I have.

[CT Performance, Inc.]

You need a min 4.10's, did you get the HD Ford trans or the std.