It sure looks like an "industrial" version of the 4-1000A or 4PR-1000A. Many time the "Y" means it's the industrial version. ie. 3CX1500A7=8877 YU-158=8877 same tube, industrial version **************Feeling the pinch at the grocery store? Make dinner for $10 or less. (http://food.aol.com/frugal-feasts?ncid=emlcntusfood00000001)