[BCreekDave]

I made up a spring stretcher in the tool shop at work.
Basically a threaded tube with a long bolt and end adapters that touch as little of the spring as possible.
Thread the bolts all the way together, insert and unscrew and that stretches the spring out. Blast,clean and phosphate (or plate). When finished, thread back together and remove.
Were the springs manganese or zinc phosphated? Mines a '70.