Am I right in that it can only go in one way during reassembly?

Yes, it will only fit in one way.

Well, if you have a hammer....

Yup one way only

I found that out when test fitting a new connector to the 48, since it had to be custom fitted (overtravel stop) the slide wouldn't come off the lower without me taking the slide apart while it was on the frame so I could get it off and the connector out.... Made for lotsa Fun.....

It’s what I thought. I put two back together and just needed to make sure. Didn’t want to tear the slide down again just to look.