The latest replacement pumps have a sort of carbide blasted finish on the body. The aluminum is darker in color, not shiny like older pumps. There is a "web" missing from the triangular area that bolts to the front cover. However this is the body of the pump and that part is GOOD! the shafts that I've seen fail, have no color hardening marks just below the upper guide bearing that runs in the aluminum front cover tube, AND the larger dist. drive. Good new ones, have a bluish hardening marking below this bearing area AND EITHER the small or larger dist drive top. Again, there is nothing funny about the newer housings. Only the shafts may be questionable. I have in my hand a new bodied pump with steel internal gears, and an old (looks like 101) shaft, put together by a racer. He possibly broke the shaft that went with the new body. A year ago I was thinking of making up a dozen or so GTA shafts, until I found how expensive they would be due to the multiple machining and hardening steps required to guarentee they would be tough, but not break. Keith Goring was also looking at having some made up at the old euro MIG plant, but also ran into the "cost vs who will pay that much" problem. The problem with making up these shafts as an individual, is the possibility of failure either in an expensive GTA engine, or other racer where a failure could result in injury!
I have a note somewhere from a racer that broke two new pump shafts in qualifying
! The combination of heavy weight oil and high RPM, can cause sudden failure. Usually (not always) the dist not turning shuts the engine down before the lack of oil pressure does
. The closer the gear to housing, both radial and axial tolerences, the higher the load on the drive gear and pin. The pump bottoms are often lapped to decrease the axial play for more pump volume
. There is probably only a slight difference between "safe" tolerences and serious loading of the pin area in modified pumps
With normal street pumps, they should last as long as a good engine rebuild, IF oil is changed regularly, and high RPM with cold, heavy weight oil is avoided. All this is based on a properly heat treated shaft of a uniform alloy
. These shafts must be hard on the surface to avoid wear, yet have some internal flex to resist this type failure. Just my opinions based on observation