Hey guys, i just bought another 4r100 to rebuild and swap out the defective one in my 2000 excursion with a v10 4x4. The one i bought came from a 2002 e450 cutaway van with a v10, it was rwd and had the drum parking brake on rear of the trans. My first tought was i will just order a rear tailshaft and output shaft to convert it to four wheel drive, but when i got it i noticted that the tailshaft extension and output shaft look exactly like a 4x4 unit. Now i did some searching and found that the number on the rear extension is rf-f81p-7a040-bb, which actually comes up as a 4x4 transfer case adapter and the output shaft looks to be the 14" 4x4 one in it. In some rv forums there are alot of guys saying they did 4x4 conversions and all they had to do with the trans is remove the parking brake assembly and bolt on a transfercase. The issues im concerned with are all the splines on the output shaft the same for all the 4x4 ones, and because the trans id code is a 1c2p-cc / prb-fz and doesnt start with 1c3p like the 4x4 units is there any differences internally with this one? I just want to know if i need to order any extra parts when i tear it down. And if the internals are the same as a 4x4 unit and the back half, how come when i put the trans id in only lists a e350 e450 cutaway as the only application even though it actually has the same rear half of a 4x4 unit with the exception of the parking brake drum assembly which simply unbolts off as part of the brake system? Just as some extra info the id tag had a big 9p on it also and the main case number was f81p-7006-aa.