I think your probably right, I found another reference to them listed as;Hardtack wrote: ↑Fri Apr 23, 2021 1:37 amSI Equipment might have been an early name of what is now Major Surplus and Survival which has for been in buisness in the Carson/ Gardena area for years. They do mail order and operated out of a variety of open to the public warehouses in the area. The have sold MRE components by the case or in singles for many years.
When I googled "SI Equipment Ltd. surplus" Major Surplus and Survival come up so its probably them.
"Survival, Inc. (17019 Kingsview, Carson, CA 90746)"