was this style sold as a kit to convert existing signals to programmed visability?

Yeah, it replaced a standard 8" lens and visor, these are getting pretty rare as 8" signals are getting harder to find.

did 3M make an 8" version of the boxy 12" PV signal or is this it?

I think this was it, I think 3M only made a few traffic signals, the boxy 12" one, which also came in a pedestrian version, the 8" adapters, and some 12" lens inserts which emulated the look of a 3M (no PV) for regular 12" signals but had severe sun phantom issues so they were banned.

3Ms traffic line included the M123 vehicle signal that served as the prototype to the famous M131 model which was made in a vehicle and pedestrian version. I can't think of all the model numbers but then there was these 8 inch adapters as well as 9 inch pedestrian adapters. They made an 8 to 12 inch enlarger, the dynamic pedestrian signal head, the high visibility lens system for standard 12 inch heads which was pulled off the market for sun phantom issues. I installed these into a marbelite 12 incher a few years back... Let's see there was these motor controlled dual color lenses, and a special lens with an arrow etched in it so it looked like a full ball from far but an arrow up close. The dynamic ped was neat too it eliminated the flashing don't walk by displaying a walk in the street but a don't walk on the curb. I got to see one up close. I took a pic I will upload tomorrow maybe

It is 130.

Those are the 8 inch adapters but I don't remember everything else...like everything I just mentioned......

that pedestrian signal sounds like a very cool specimen! I'd love to see a pic.

Here it is. I think I have some more pics buried on my hard drive. This one is not mine so I dont have access to more pictures. I can try to locate the original advertisements though.