i have an 84 reg cab truck with a broken frame its pretty much unrepairable i found an 85 ext cab frame already stripped on cl just wondering if my truck will fit on it or what mods i would have to do to make it fit

 

You could make it work, but it would be a lot of work because you would need to move some of the cab and bed mounts and probably the rear spring mounts and shorten the frame. It would be a lot easier to try and find a frame from a truck like yours.