I seem to remember that the 2.6 oil t'stat housing used a crush washer and I think it's the same size.

Sounds like you had a hanger in the oil pressure relief valve that freed up. Must not have been hanging all the way closed, or you'd have had a worse mess. My 2.6 with a stuck relief would blow up stock mitsu oil filters (tested to 250psi +) on a cold day cold start. Also sprung a 150psi autometer mech oil gauge. Truck had 70psi of oil pressure when it was off...