I am not sure what you need to know.
I have had one since I bought my PZ-1 in 1991.
Although the documentation states that it can only be used with F2.8 and faster lenses, I had origonally contacted pentax in canada to try one out, They let me stand outside their service department and test several lenses to see if it would focus on something slower than F2.8. It did, so I thanked them and ordered one through a local store
Ultimately this TC got a lot of use on my Series 1 70-210 F3.5, as it made it a 105-350 F5.6 AF.
Later I saw a mint 300 F4 in a shop and again tried it out for AF before purchasing.
I still use mine and have posted shots with the 300F4 attached from both the K10D and *istD.
I find the best use is with flash, on the *istD taking advantage of the TTL metering. The results can be seen below
https://www.pentaxforums.com/forums/106132-post4.html