How long were they made? How many were made?

I would suggest editing your post and remove the first part about wanting to purchase and then post a proper WTB ad in the classifieds.

Please read the final line of rule #11 at the following link:

RULES

Well the book shows -
10-1 1959 introduce 4" heavy barrel.
10-2 1961 Change extractor rod thread right hand to left hand thread on standard barrel.
10-3 1961 change extractor rod thread on heavy barrel and front sight changed from 1/10" to 1/8" 0n heavy barrel.
10-4 1961 1962 trigger guard screw eliminated on tapered barrel frame.
The next heavy barrel change was the 10-6 in 1962- eliminate the trigger guard screw.
So they didn't make them for too long but no idea how many were made.
Maybe one of the guys can tell you.

Oh, welcome to the forum.