My DS came from a 2WD Chevy Blazer. I had to search for the correct model and match the number. The first time I found one (currently in my 1963 C10 short bed) it was just laying on the ground at the salvage yard. It measured close enough that I brought it home and was delighted at how well it worked. I searched the web and found info suggesting it was used in 2WD Blazers. This last DS is one I personally removed from a 1999 Blazer. Not every Blazer I checked had the same length DS. I compared things and documented my findings.
Please note that a T5 is about 3” longer than the 1963-66 factory 3 speed MT, so the comparison pics should make sense as to why the Blazer DS is the correct length for my C10 with a T5.