I bought this model 88 some time ago. It is a French police surplus gun. The frame is based on Ruger Security Six/Speed Six/Police Six frame.
The fire control group does not drop out the bottom but the gun has a side plate.
These is a stud in the frame that the yoke closes over.
The grips are Traush and are ugly but after shooting the gun they fell great. The ridge on the top keeps your hand from moving and makes follow up shots easier.

The MR88 is cool. I own a MR73.

You could probably delete your other post since no one has added to it.

That is an interesting gun. If you watch the movie "15:17 to Paris" from Clint Eastwood about the train that was attacked by a terrorist who was overcome by three US service members, the French Police responded when it came to a station and you will see them using a stainless Ruger Revolver. I was very surprised to see it but now I get it.

I don't have any experience with MR88 but have Two MR73. They are right there with Korth in being the finest revolver made. I'm sure the MR88 is also a very fine revolver.