from matt69cutlass at oldspwoer.com
Re: Drilling 200-R front drain
Remove the pump, disassemble and remove front bushing and seal. Take a 5/16 and enlarge the drainback hole, take the drill and slightly "wiggle" the drill to elongate the drain hole. Flip the pump over and drill the intersecting drain hole to match the front. Once this is all done install a new bushing, making sure it doesn't cover the drain hole (now you see the reason for elongating the hole) and install a new seal. A seal retainer from a late model 4L60/4L60E would be a wise addition.
Thought this of interest.
also, this. Kinda long but it has a bunch of part numbers and such. I signed up for the mailing list but was unable to find his posts on the build from he77. Maybe someone else has a link.
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