You can get the entire set of manuals (Service and Parts) for the 337B (Actually the 336 and 337 through 1972) on CD for about $25.00 from McCurtain Technology in Tempe Arizona. Check it out at
www.mccurtaintg.com.
I bought the CD and it is great... you can print pages from the manuals and mark all over them and you still have the original!