I crawled under my truck and found the number P52119091AD RFE on a sticker. From what I've read I either have a 545 or 45 rfe but I have no clue which and the number doesn't seem to indicate either one going by number alone. Anyone know which tranny it is? Got a 140k on it and she's slipping in OD with even the slightest hill or breeze.

 

What year? What engine???

 

Sorry brain fart on my part! It's a 2003 Ram 1500 4x4 quad cab with the 4.7L.

 

'03 marked the first year the 545rfe was used on the 4.7 Ram 1500. It replaced the 45rfe used on the '02 4.7s. The 545rfe is basically the 45rfe but with a software update adding in essence a 2nd overdrive gear.

It's proven to be a very reliable transmission (which is a pleasant departure from Dodge truck transmissions that preceded it). Usually, as long as proper maintenance has been performed it holds up as well as any other 1/2 ton truck transmissions on the market. It is picky as far as the filters go and like any other automatic transmission will give you trouble if you leave the fluid go unchanged too long.
Usually if you see a problem with one, it's a solenoid that goes (an inexpensive repair) or the torque converter goes out (probably the only real weak link in this transmission)...