From what I understand, It is very common for aftermarket driveshafts to not be straight. They eat up pump/midshaft bearings and shake. I also think that if the shaft doesn't get installed on the pump/bearing correctly, this could cause a wobble too. I took a drive shaft out that wobbled like crazy in the pump and it was fine when checked on the bench. (there was no bearing play either) I installed it in another pump and it didn't wobble at all. Could be an issue with aftermarket bearings not machined correctly?