Try canadianrodder.com. If you want anything from back in the 20's up to the 70& 80's.
How about this....
Mopar big block 400 swap package complete
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Selling a complete, good running 1978 Dodge 400 swap package. Includes complete engine, air cleaner to oil pan, truck exhaust manifolds, matching short tail shaft 727, KD linkage, all pulleys, PS pump, fan, rad, alternator, starter, engine mounts. Everything you need and it runs well. Located in Kelowna and I don't do house calls so you'll have to come and get it. $500 for everything. Can be test driven for the next week or two but I'm pulling it pretty soon before the neighbors lynch me. Ph 778-753-2734 or; moparnutatshaw.ca
I also have a 4.10 DANA 60 out of the truck as well, it's quiet and would be great replacement in your 3/4 ton truck or good for narrowing $150.
Thanks
Sheldon