blind bolt installattion reduction starter?

I am thinking about installing a reduction starter on my 1500 but am wondering what a blind bolt installation means? The place that is selling them states "Most are quite easy installations requiring no modification of the vehicle other than small wiring changes. However for the 1500 midget it will require a 'blind bolt installation' which is not quite as easy, but still not a problem" .

Can anyone describe what that actually means as far as doing it? I assume the blind spot is the top bolt right? could one weld or braze the bolt to the unit so one doesn't have to deal with having to secure two sides while trying to tighten? The unit in the picture also looks larger so is it difficult to get into position? Does one slip it from the engine compartment downwards or from under the car? Thanks for any info.

Probably the top bolt. I think those starters do require a little bumping out of some sheetmetal. I've never installed one though.

Blind bolt means it is not drilled thru, IE: threads are in the starter or bellhousing