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I got a couple cars off ebay. Both have 6-gear transmissions. I have only had one of these before and passed it on without messing with it, in favor of stealths.
I have 3 observations/questions:
1: the diff gear fits very loosely on the inner diff plate. using a brand new kimbrough gear there is quite a bit of movement. It seems like it is ok with the 32p gears, but there is definately too much variance to properly mesh 48p. Is this normal to have some float? is the hub worn out? I tried several spurs, The white spur it came with has the least float, the kimbrough 60T has the most.

2: the far side of the upper shaft on both trannys has a tapped hole for a retaining screw instead of a ridge for an e-clip. Is this something that was a running change for AE, an aftermarket top shaft, or a home-made solution?

3: on the outdrives one trans had the felt washer and retainer, the other had bearings. Is there any reason to use one vs the other? Will the idler gears last longer with the outdrives being better supported?

Thanks,

1) I think they all have some play in them but you're right its better for the 32P than the 48P. I have found that the Robinson 56 tooth in the 32P were the best gear for the 6 gear that i've run. I think if the diff starts to slip it will quickly wear out the center and the ball holes and the entire spur will float as you say. It also could be worn out hubs which might make the entire diff wobble.

2) must be a home made thing as i've never seen an AE change and the only aftermarket change i know of was a longer shaft so your diff nut could seat better and not be hanging off the end when you ran your diff loose...

3)I've ran booth and i dont think the idlers wear much differently but you keep out the dirt a bit better with bearings...the big advantage with the bearing support is that the outdrives wont flex and pop out a drive axel in a crash like it might with the felt...but if the bearings get dirty and start to bind up you'll have probs and might not know it right away...also i've had the bearings put a side load on the gear case and caused internal friction and wear between the outdrive gears and the case wall if they are pressed in too much...

Used to run 48P spur on my six gear trannys with no problems. The gear floats on the diff balls and all have some wobble without the pinion gear engaged. Can't remember who made the ones I ran but they fit great. Trackmaster made a long diff shaft that had a phillips head screw instead of an e clip to retain the bearing. I would for sure use bearings on the outdrives but like superfly said, keep them clean and lubed. Had one bind once on my dirt oval car years ago and it drove EVIL!!!!