MIke, yes, the suffix U was a big truck (series 6000) 235, and designated Loadmaster (vs Thriftmaster).
Gavrin1, the engine would have originally had solid lifters. Good to double check, but as I recall, the '56 235s only had the oil galley drilled to accept hydraulic lifters if they were originally equipped with them (so only passenger car service in '56).
Doug
