Eaton HO72 with load bolt question

[wtb853]

I currently have an Eaton rear axle with a leaking pinion seal and 4.57 gears under my truck. I have been waiting to address it until I can build an additional 3rd member with 4.10 gears and a No-Spin to swap in. I finally have the pieces I need and am ready to have it built.

The open 4.10 geared 3rd member came from a '71 motorhome. I'm assuming it is an HO72 given the size of the brakes and it does have the load bolt. My plans are to swap its gears and the No-Spin I have into one of two fresh housings I have been holding on to. One of my hot-tanked housings has a load bolt and the other does not. I understand that almost all Eaton rear end parts swap regardless of weight rating from the 40s up to 1972.

My questions center around any nuances on coupling the 4.10 gears out of the RV and No-Spin with the "load boltless" housing I have. I figure less to leak; less to monkey with. Load bolts and ring gear deflection won't ever be an issue for my purposes. However, I don't want to have this cobbled all together (new bearings and seals) only to find there is some issue the experts here could have enlightened me on.

Also, why the additional (6th) unthreaded hole in the load bolt housing where the cast iron pinion cap bolts on? Thanks in advance!!

[wtb853]

Pic showing the two housings and the extra hole in the wood crate

[Wrenchbender Ret]

I would use the later model with the load bolt. It is a good feature to prevent the ring gear deflection. The extra hole is probably for the lube to get to the brg. or to drain back.
A little RTV on the bolt will prevent any leak.
George