slant six 3sp. to 4 sp. conversion

Small block trans will work. It just requires a slant bellhousing/flywheel/clutch. Probably the best 4 speed for a daily would be the 833 OD. Should be able to get that out of a mid '70's A or F body. Lots of trucks came with it too, so you may want to check slant 6/4 speed trucks for a bellhousing, flywheel, etc. There is a lot of good 4 speed info here http://www.bigblockdart.com/techpages/4sptech.shtml.