The 48 could not lug it didn't have enough gears!Good to hear the lugging is something experienced by you all too. I just underwent a 68rfe swap from a blown 48re and the lugging on the interstate is something I virtually never felt in the 48. I bought the 68 tranny remanufactured https://reman-transmission.com/transmission-codes/?code=68RFE and it has been good so far other than the lugging. Gas mileage has been way better though obviously