I found one on eBay for my 1973 150L, think it was about $20. I used it to replace the one with a 1971 date on it that was in plane when I got it. As near as I can tell they are identical, If i was not planing to do my instrument check ride in the plane I would not have bothered swapping it out but the DPE that will fit with me in my 150 has a reputation of picking at certain details of the plane being used so I decided to have one less thing to pick about.