We see some 370/12's have different dimensions of the bridge to tailpiec and some have gaps between 3 pups and some are nearer ?

it does not seem to be for certain years. ? Some MG or some VP MG but not consistent in names.

is there certain models the bridge is moved forward and all PUPS are almost side by side for some reason ?
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I think the difference you are seeing between the pickup spacing could be down to if the neck is either 21 or 24 fret length.
Obviously if it's a 24 fret neck with 3 pickup's they are going to be closer together than on a 21 fret model.

I don't think the bridge position has ever moved as Rickenbacker's scale length has remained unchanged at 24 3/4.

Yes, the difference is in the 21-fret necks and the 24-fret necks. Since the guitars have the same scale, and the bridge is in the same place, the way that the 24-fret necks are made is to inset a longer heel into the body to accommodate the extra three frets on the fingerboard. This forces the neck pickup to be closer to the bridge, and so therefore the mid pickup must be moved as well.

I experienced the opposite problem on my 1981 320. The '70's and '80's 320's have a 21-inch scale, 1/4 inch longer than the 60's and reissue 325's, which have a 20 3/4 inch scale. But the same neck inset with 21 frets and the same pickup routing template was used. So my bridge pickup was 1/4 inch farther away from the bridge, as the bridge was moved the 1/4 inch towards the tail to accommodate the longer scale. And for decades I wondered why my 320 did not have the "bite" as the older guitars. Jangle, yes, but no treble pickup bite. I finally figured out it was due to pickup placement. So, at the risk of heresy, I routed out the slot in the top 1/4 inch towards the bridge and moved the bridge pickup so it was in the same relative position to the bridge as the 20 3/4 inch scale models. I got the bite back to go with the jangle, and then trimmed the middle pickup rout to split the difference so the pickups were evenly spaced.

Yes, the pickup placement can make a lot of difference with regard to tone as well as aesthetics.

All answers are correct including mine. In the early guitars of the 360-370 series, the Byrds style, the end of the neck was flush with the front edge of the body. The revised design of the same series moves the neck into the body by the space of the last 3 frets of the neck, requiring the neck and middle pickups to be moved back towards the bridge. Whether this relocation of the neck and middle pickups changes the sound I don't know, since I have not compared the revised design sound with the sound of my 1966 370-12.

Yes. It does change the tone. The tone is more hollow sounding on the 21 fret necks and more present sounding on the 24 fret necks.