Yes, OP said he has a 1974 904 in a '68 Barracuda. Which shouldn't matter, all '66 and later (non-cable shifted) trannies that I've seen used the same speedometer drive housing (okay, maybe not some of the late OD trannies). Beginning in the late 80s or thereabouts, Mopar started using a screw-on Vehicle Speed Sensor to accommodate their first rudimentary computer controls on the Dakotas and Rams, maybe others too. These attached to the normal trans. speedo drive, but had a smaller speedo cable nut fitting on the output side of the VSS. This is the only setup that I've seen that uses the smaller cable fitting (emphasis on "only one I've SEEN" :) ) on a RWD vehicle. Coincidentally, it's the same fitting that was used on the speedometer end of the cable on '66 and earlier cars before they went to the push-on connector...
