Soligor I-S Mount ?

[Lloydy]

I came across this Soligor 135 / 2.5 on ETSY and then noticed it has an unusual mount, it's not the TX type but appears to be a Soligor specific mount, and one I haven't seen before - probably the Soligor U/S Universal System Interchangeable Mount

https://www.etsy.com/uk/listing/237084214/vintage-soligor-135mm-f25-tele-auto-lens?ga_order=most_relevant&ga_search_type=all&ga_view_type=gallery&ga_search_query=soligor%20camera%20lens&ref=sr_gallery_2

It looks like a nice lens, possibly one of the Soligor Golden Series as mentioned here -

http://forum.mflenses.com/viewtopic.php?t=17859&view=next

but....the two gloss black Soligors I already have are '1' serial numbers and probably Tokina, the ETSY 135 is a '3' and probably SUN, as is the one pictured in the old MF topic, and every other one I've seen when looking for information on this 135 / 2.5

Soligors are confusing, and the seller doesn't ship to the UK, so that's made that decision easy.