L1500 reverse gear

[tswirka]

Hi all, my 1500 has been jumping out of reverse. i read a post about it maybe the reverse idler gear. when i removed the shifter plate and drained some fluid i could see the gear is almost gone. My question is : to remove the shaft that the gear is on do i break the tractor at the trans bell housing or at the rear end housing, or do i have to break both and put the gearbox on a bench?
Does any one know if the 175's gear is the same?
Thanks everyone for the previous help with the filters.(that was the easy part i guess!)
Todd in Memphis