Need further definition on what you consider a mod.

As an example, the white face of the clock wass not part of the production run, so I would consider that a Mod, but white face clocks did come on prototype and sample games so mabye you consider that stock.

Same with the plastics in the spiral lane.

So are we talking things that are diffrent when comparing a machine to a production version of Twilight Zone or thinngs that are diffrent compared to a sample/protype version of the game?

Here is a picture of a smaple playfield:



I don't see those posts your mentioned.  

So going to be pretty hard to accuratly guess what you mean, this is more like guessing home many jelly beans are in the big glass jar  

So my guess, if you don't include the spiral plastics, posts in the pop bumpers, and white clock face and you include the decals on the targets as 1 mod as opposed to each decal counting, the decals on the flippers as 1 mod, and the lighting on each individual ramp as one mod.

From my count you have

35 mods in your jelly bean jar.... I mean twilight zone.