[bkhpah]

Let's try and set the record straight on the "YENKO" tach. There are two versions of the SW tach that Yenko would use. The model 977-J that was the pedistal mount series with the black face with 8K limit, and the model 970-B the custom face 8K unit. A black and white version of the 970-B was called the 970-J. All of these tachs required a ignition monitor box. The box Yenko used was a 990-A or the 990-D. Many types of SW gauges could be ordered as well. The Custom face line came in three versions. The "utility" which was a cheaper bottom pivot gauge at 2 1/32" diameter, the "deluxe" were a center pivot model at 2 1/16" and was more accurate. And the "racing" 2 5/8" was the top of the line. These were also available in the black and white versions. It is hard to tell what was used more, but I would think it was whatever they had in stock at the time. But after May, Yenko had the GM 7K unit and the center fuel gauge installed by the factory eliminating the need for the add on tach. Also it is important to note that Bill Smith (Yenko's head man) was dealing with Dixco at the time and some cars may have used this line as well. We are certain the the 70 Dueces used them. Now isn't that simple! Anyone else have other versions?
BKH