John, the linkage on the top of the carb for the Acc pump was disconnected. I fixed that. There are no adjustments on any of the rocker arms so I have to think that the lifters are hydraulic. I know that it should have solids in it and it is the original motor but it seems that there are hydraulic lifters in this motor.
The truck is titled as and looks like a 66 but the ser # info says it is a 67. It may have been purchased in 66 butbuilt in 67, who knows? Also, when I noticed the accelerator pump linkage off, the linkage that feeds into the top of the carb has a rubber bushing on top and it was stuck in the down position on top of the carb. I did have to replace the fuel pump as the diaphram began to leak. Maybey the carb has also developed an internal problem. I will take your suggestion and rebuild the carb before I continue on with replacing the lifters to fix the problem.