Hey y'all this is a question I see pop up on here and I've never seen it answered, I just posted the below in a thread on the Triple Diamond forum and wanted to copy and post it here to get more traction.. Is the only difference between the Eaton FA-50 in '50s and '60s civilian heavy all-wheel-drive trucks and the WWII-era Eaton FDK-1361 (used in the M-5H-6 deuce) the trunnion oil seal? I've always assumed they were identical axles, but from all the photos of the FA-50 I've seen and in Rob's walk-through I've never seen or heard any mention of the trunnion oil seal (IHC 108310 H/Eaton 24287) that's shown in all the M-5H-6 manuals and coincidentally have never been able to find one or a modern solution. All the other seals in the military axle are identical to the FA-50. Here are two very similar questions: Is there a slight difference in the design of these two axles that eliminates the need for this seal or did they just decide it was unnecessary to begin with?? If the two axles are indeed the same and the FA-50 does have the trunnion oil seal, has anyone figured out a replacement solution? I'm preparing to tackle the axle seals on my M-5H-6 and I want to have everything on hand that needs going into it. Since I posted the above on the other forum, I found a photo that Dave Ball posted of a NOS seal (I saved the image and attached it here). If Dave or anyone who has one can get the OD/ID measurements with a digital caliper I'd be happy to do the legwork finding a cross-reference or at least a modern replacement.