I have two Sermac pumps that I am going to convert over to Putz s-tubes.  What I lack is the90mm  splined hubs that will be put on the Sermac swing arm.  I can purchase new Putz swing arms and machine them down but was hoping to find a less expensive way.  Anybody have old Putz swing arms that maybe have bad sockets but good splines.  Any ideas will be appreciated.

Wow you are going to turn a turd into a priced jewel. Can you take pictures and let us know how it goes? That Sermac will love you.

In the 60's my dad put a big block in a Corvair and ran 7.68 in the quoter mile.

I have 5 Schwings and 2 Sermacs.  The s tube and the related partson the Sermacs are turds but they have been successfully converted to Putz big mouth s-tubes by others and we are doing it also..  Believe it or not, We have had less problems with the Sermacs since new than the Schwings. Parts are a problem but other than the s tubes we haven't neede many parts. They are much simpler without all the wonderful electronics that Schwing feels obligated to put on their pumps.  My first Schwing was a black and white 36 with a corded remote and if it had oil and deisel it would run and finish the job.   To repair a joy stick costs a few dollars for switches instead of thousands for a proportional joystick.  It was harder to learn to run smooth but it could be done.  KISS is something that I wish pump manufacturers would try to do. Computers are pretty on new pumps but nightmares to fix or replace and the old pumps somehow ran well without them.

By the way I had a stock corvair and it would do 7mph in the quarter

That car must have been what Ralph Nader had in mind when he said Corvairs were unsafe at any speed.

that was a funny car in more than one way, it had a built 427 in it.