Thanks for the comments and information guys...
I found an old '57 Chevrolet Truck manual that has been missing for years. amazing what you can find when you ask yourself a question you can't answer.
Page one tells me that the engine source, production date and type desigantion is stamped on the right front of the V8 block.
Under Engine assembly p 6-84 I see that there were four engines with full specs available available: 235 - Thriftmaster, 261 - Jobmaster, 265 - Trademaster, and 283 - Tashmaster.
At page 6-88 there is a description of a description of a Loadmaster engine. It is painted red with 4" bore and 3.2" stroke. compared to 3.75 and 2.298 for both the 265 and 283.
At page 6-39 the Taskmaster 283 is described as standard on 5,7, and 8000 and optional on 6000 while the Trademaster 265 was optional on 3 and 4000 series trucks.
The text would indicate that Task master and Load Master were used for models 7000 and 9000 as well as 8000 and 10000.
So far, it looks like the shop manual would indicate that the 235 was standard and 265 optional on the light trucks. I will be interested to find out if some 3000 series trucks were delivered with a 283.
Does anyone have further research material?
