I'm swapping from a column 3 speed to an 833 OD and will need to cut a hole in the tranny hump driver's side to feed the shifter. Does someone make a bolt-on hump piece for mounting the shifter plate/boot, or will I need to get a welder to fabricate something?

I don't have an answer for your questions but if all else fails, you should be able to find a hump in a salvage yard truck. I see the A833 overdrive trucks here in Minnesota salvage yards.

Go to the junkyard, peel the carpet (rubber mat?) back on any Dodge truck that you find with an A833OD and youll likely find a fiberglass transmission hump "extension" that usually is held on by a few screws. Been there done that. Youll want to look at trucks between about 1978-1987.

Fiberglass
That is news to me. I'll have to take a look next time I visit a yard. I just assumed they were all steel.

went to a junkyard. Found and removed a fiberglass hump from a Ram 150. I hope it fits my D100...

the Ram 150 shifter hump wasn't a perfect fit. I suppose I can trim it. Hacksaw?

What year trucks are we talking about here?? Within a particular body style (61-71,72-80,81-93) whether a truck is rated at a 100, 150,200,250, 300 or a 350, the cabs are the same. Only the suspensions and axles differ, although SOME 300s/350s "1 ton" had heavier framerails. I have also heard that the cab itself will interchange all the way from 72-93, although I've never tried it myself.

My truck is a 78 D100. The donor shifter hump was from an >80s Ram 150. My floorboard hump looks to be about 2-3 inches lower than the Ram's.

While all the cabs 72-93 will physically interchange, there as many as three different sized tranny tunnels, depending on 2WD or 4WD, and transmission.

There was a discussion on this going on over at Moparts, it seemed the concensus was there are three different trans tunnels in these year trucks, 'small', 'large', and a 'large boxed' tranny hump.

Sounds like you have the 'small' trans tunnel (as does my '87--2WD, slant/904) and you got the shifter box from a large tranny tunnel. IMO if you can trim it and make it work, go for it.

-S/6

Since I have the small tranny tunnel, does that mean I'll need to cut out the whole tunnel to fit the 833? That tran is a little larger than my current three speed.