Tractor Repair: compression test, test gauge, compression test

Question
I have a 64 ford 4000 diesel and was wondering if there is any way of doing a compression test on it, if so how

Answer
  Remove the injectors and install the correct adaptor for a compression test gauge into one of the injector holes.  Attach the gauge and crank the engine over until the highest reading shows on the gauge.  Repeat the procedure on the rest of the cylinders.  I do not have the specs on what the compression should be, but most diesels are between 350 and 400 psi.  All the cylinders should be within 10 percent of each other.