Many years ago, when we were running the Veco 19, K&B 6.5, and OPS 40 and 60 marine engines, the choices for glow plugs were limited. I ran the K&B 1-L in just about everything. If my engine was taking plugs, I'd add a head shim.
Then there were the McCoy glow plugs, OPS glow plugs, K&B HP...