Anything's possible! We tried this for a while, thinking they might last longer than the stock savage gears but it didn't work out that way.
There's
lots of shimming and general screwing around you've gotta do. And you do have to use the 8x16x5 bearings (they last longer anyway). The pinion is gonna have to be shimmed further into the bulkhead. It's real important to get this
just right. Also it doesn't like to be shimmed up by the teeth because of the stop-gap, so you can test fit everything with a spacer/sleeve, which you'll have to make (sorry can't remember the exact size), get it all
perfect and green locktite the spacer on or you can stick a couple shims under the inner pinion bearing, (I don't like that much but....eh...for your truck it's ok. hehe).
You can't use the pin that holds the input drivecup because the hellfire pinion has a flat spot instead of a hole. The pinion won't be sticking out far enough to just drill a hole in it. It doesn't stick out much at all in fact. So you've gotta use a set screw or cut the pin part off the original fastener. I can't remember if we used the stock savage drive cup or something else.
I know I said anything's possible but, nope you can't mix-n-match because the hellfire gears are semi-helical cut and the savages gears are straight cut.
If it were me, I'd probably do my best to figure out some kind of gear reduction at the clutch and put cen diffs in it which will produce a
higher ratio (2.89:1), but are tough as nails.
Ok, I wanna see some pix of this beast!!!