Usually, between the front fuel tank bracket (the high bolt on one) and the front bed mount (just in front of where your rear jackstands are) is about the best place to shorten one. You can take as much as 10" out of that area and still use the front bed mount and the Dakota tank. If you use a Dakota tank, you will need to notch the back of the cab to clear the front of the tank (4" above the floor and from the center of the cab to just outside the frame rail, about 6" into the cab). Most of the 50s trucks had a fuel filler hose that went through the cab floor at that point, so you would have to patch that hole anyway. If I could get my pictures off my old camera, I could show you a picture of the cut out and the floor patches. The biggest Issue I see with using the original gas fill hole in the cab is getting the Dakota fill hose to it and still have enough drop to fill the tank. The front bed mount cross member will be what causes the biggest issue..

Most often I've discovered that you can keep and use the back 1/2 (the front bed mount) of the cab/bed mount bracket. Usually the cab mount part is too high, too far back, and not in a good location for a rear cab mount on old cabs. I usually make a rear cab mount bracket (in the past I've used a piece of 3" wide channel, or a 2" wide piece of angle iron that got welded to the frame). Match up the new bracket with where the original rear cab on the cab your using are located.That way, unless I'm replacing the entire cab floor, I can re-use the original rear cab mount floor bracing and just update the actual rubber cab mount.

For about $100, you can buy a set of Energy Suspension replacement cab mounts for a Dakota. With the kit, you get 4 rubber bushings with a steel insert that goes between the frame brackets and the body with 4 rubber pieces that go under the frame brackets. You also get a pair of radiator support bushings with the steel inserts and a pair of the rubber bottom bushings. You need to supply the bolts and washers, but the bushing kit is pretty cost effective. You really need to look for the 6 mount rubber kit, they really want to sell you the $250 all inclusive kit. Gene