Been reading and not getting a clear answer. My manuals on CD are coming!!

Have an 81 240D, PO did a 300TD swap I don't have a tachometer in the 240, question is can I take a dash pod from a 300D car and just do a complete swap, will the 240 wiring harness have the needed wires for the tach, other gauges would just be a swap of plugs I'm guessing....if not on the tach I'll have to wait on the manuals to see where the tach trigger is on the 300TD engine and go from there..