I need new heavy duty coil-over rear shock absorbers for my 1980 Fairmont Sedan. For many years I've purchased and installed 'Monroe Sensa-Trac Load Adjusting Coil-Over Shock Absorbers' part number 58428. (see attached)

http://www.monroe.com/en-US/e-catalog/58428/

However these shock absorbers are apparently now obsolete and I haven't been able to find them anywhere. I tried 'Bilstein' also but no luck there either. Does anybody have a good part number and brand name for a heavy duty coil-over rear shock absorber for a Fox Chassis Ford (something that will fit my application)?

I'm a little surprised and very disappointed that the Monroe shocks that I've been using all these years are no longer available...