I replaced both lower hinge springs on my 1950 Chevy COE with reproduction ordinary Advance Design springs. You can remove the broken spring easily but to replace the new one you need to press out the hinge pin. I had a shop with the proper tools to do it for me. I don't recognize the spring depicted on page one.

Kent

1937 Chevy 1/2 ton
1942 Chevy 1/2 ton
1947 Diamond T Model 509
1951 Chevy 1/2 ton
1950 Chevy COE Model 5700 ~ "Barney" ~ And more pix