You could be right. Below are the illustrations for the two pumps. Unfortunately they chose to show a front view for the 1-series pump and a rear view for the 2025R pump but they look very similar and the gasket (shim) is the same part number for both.
I never realized that the hydraulic pump for the 1-series and Gen-2 2-series attached to the rear of the transaxle. I assumed it bolted to the engine like the pump on my 2720. Then I looked at the Gen-2 2032R/2038R and saw that it looks like their pumps attach to the front of the transaxle and not the engine.
1023E / 1025R (Early serial numbers)
1023E / 1025R
2025R (Gen-2)
2025R (Gen-1)