Trailgear dual case adapter - dual row bearing upgrade

Thought I'd put this out there as an FYI for those with the trail-gear dual case adapter. You can fit a MRC 5209-CG dual row bearing in place of the single row bearing bearing it comes with. Should help resist more axial loading.

Just had to machine down the thrust washer to makeup for the thicker bearing. Also gotta ditch the blue bearing retainer and use the same hold-down bolts on the external snap ring of the double row bearing. Don't know why TG doesn't spec these adapter with one to start. Been running it like this since December 2025 with no issues.

Reached out to TG to let them know of my findings, but go figure they didn't seem to care.

For context, I'm running the marlin 4.7 XD gears with TG adapters on my W59 with the factory chain case in the rear.



Original setup with the blue retainer ring.


There was what looked to be a weird heat affected zone on the coupler where the bearing rides. Wasn't sure what to make of it so I just threw it back in as-is.

Great tech, Thanks for sharing.

This feels like some old school pirate tech.

I used the same bearing (MRC 5209CG) in my dual case setup from Inchworm/Marlin years ago. It held up great. This thread on ttora was getting some attention around the time I was assembling things so I just swapped it in instead of risking it. It was a direct swap, no machining needed.

Yep. I was the one that did the digging to find the right bearing back in the day. Cool to see that it works on the TG setups with a little work.

Afaik my old truck is still running around with the mrc bearing with no issies. My new rig is a 4runner has a AA/marlin dual row adapter and it was making some noise wheb I got it. I upgraded it to a mrc bearing too with no issues.

That max cap bearing has no buis being in a transmission.