Re: 4r100 build - need suggestions
I wouldn't spend a penny on it until I crawled under it and checked the transmission build date.
2001 models with 4r100's built between 7-27-00 ~ 3-23-01 have a type of one way clutch (mechanical diode) which are prone to failure, the only cure is a full rebuild.
The build date is on the tag on the drivers side of the transmission.
3rd row down, you'll see BD then a number 0 = 2000, 1 = 2001, then a letter, A=Jan, B=Feb C= March etc, then two number's - 01-31 = the day.
01 F-250 CC 4R esof PMT AIS, pine tree air freshener,
some other stuff not worth mentioning .