What year was White superlock 534 serger model 534W-A manufactured?

It was during the 1980's I am certain. I got my Master's degree in fashion design. The only sergers that were available at that time for the home-sew market was a homely little serger made by Babylock. People that had them liked them. None of my fellow grads students had one, but we were all interested. The first serger that I bought was a White 534 in 1987. (I still have the receipt and I still have the serger. It works great!) I remember that it had been out a little while before that. I can't remember how long. It was listed as the best serger on the market in consumer reports for something like 15-20 years. The 534 was the first easy to thread serger for the home market and was definitely that top serger of its time. Mine will not stop. It is amazing!