Correct Door Jamb Switches

I believe from the Standard e catalog that the "T" is just a designator of their less expensive product line.

Put the non "T" one over a vice and use a block of wood to tap on the fully compressed plunger maybe it is pressed in a bit tighter then your sheet metal can stand.

But unless it is made incorectly it is self adjusting

The "T" designates it to be the:

"Standard T-Series is a competitively priced line containing some of the most popular part numbers to help you meet your market needs..."

Vs the non "T" which is the:
" Standard® is the premier professional engine management brand in the automotive aftermarket today. Standard leads the way in advanced automotive technology with more than 40,000 products for complete vehicle coverage..."