Splitcase diagnostics

[PEPPE]

i have 2 cars with splitcase transmission. i should have to open them and repair, but i am not familiar with early trans.
both shift well, with no syncro problems but are both noisy.

first (55) has no noise in idle and neutral but has noise in drive (with load) crescent, less in 1st, worst in 3rd/4th. very slight noise in deceleration.
second (60) has noise in idle/neutral, that goes away with clutch, slight noise in 1st and almost nothing going up in gears.

rotating the wheels by hand both has some noise, so i assume diff bearings may be "proven". no metal in oil, so i presume R/P can be good. here is my question, which bearings will be surely damaged?

[Dougy Dee]

The 55 has a 3 piece front Mainshaft bearing. 57 and later are 1 piece assembly like tunnel style MS brg. Noise could be coming from this brg.

The 60 could be MS brg too but I'd be checking the throwout bearing first.

57 and later has a different rear Mainshaft bearing from 56 and earlier. This bearing is located by a dowell pin on the earlier trans. Snaprings locate the later on the mainshaft. The case is different too as the later bearing has a larger OD.

Also 3rd and 4th gears have different tooth counts although the overall gearing is close.

As a side note: I am looking for an early style mainshaft for my 56 trans.

[PEPPE]

the difference in cases, blocks me from mixing the good parts and repair at least one trans. so it looks i will have to open them and look the parts for each.