The next level of detail is that the same timer is used on many systems on many aircraft. Each manufacture has their own part number for it. I can't remeber the exact how I got to it, but as I recall, I had several part numbers for the same item. By searching the internet, I found a site that was showing it as new but surplus stock and I was thus able to get a good price for it. I woudl have to dig for the paperwork, but I seem to recall it was about $120 at the time.
Regards - Dave