Which Steens Taco is this Exactly

[Robertt8883]

Saw this Taco available ultra low serial number S015 clear as daylight
Is it a Taco T-100 or ST-100 or a Taco F85 Matterhorn.The Matterhorn swing arm is different then the T-100 and ST-100
Engine was just recent after thought Add on obviously not correct
Cannot get pics to load so based on serial Number

 

[SimpleTom]

S015 is all there is? Usually the first character is a digit like "5" for 1965.

 

[CarPlayLB]

My ST100 is SO89. I believe they were all built in the early 70's