656 Block Heater issues

[Chuck Hilton]

Having a tough time getting the right block heater for my 656. First try was Kats 11614. Physically would not fit. Next was IH 106725A1. Not deep enough to get past freeze plug bore. Not sure if it is actually the IH part. It's stamped LR1843. That seems to be Zero Start product. Do I have an unusual block? Block measures 1 1/16" thick at freeze plugs. Also some of the bores neck down to a smaller size at the water jacket. Picture is the 106725A1.

 

[MARK ROBKE]

Maybe, as an alternative, consider an external heater that plumbs in to plugs in the block and head via heater hoses. I think they work better and faster, too. Mark.