It is a detroit. 6 cylinders of 53 cubic inch displacement in a V conviguration (i.e. V6).
Don't know the years of use.
6-71 (straight 6 with each 71 CID, lots of torque, run forever, noisy as ...)
4-53 (nice in the newer oliver 1900's)
3-71 (nice in an old oliver 99 super GM)
