Austin,

The J in the engine serial number that Mike posted as 235 with 3-speed transmission also refers to the engine being a truck Thriftmaster 235 engine. All truck 235 engines had mechanical lifters (except, maybe truck Thriftmaster 235s in a Powerglide truck - that code would have been JH).

http://www.1954advance-design.com/chev-specs/1962-t-ser-ID/