Strange sleeves in Hemi valve guide

[Ifixmycarmyself]

Here is one for you oltimers. I'm putting together an old 426 hemi. Iron heads. One head has ordinary k-line sleeves but the other head has threded sleeves. Believe they were called Winona before Van norm bought the patent or whatever happened. Does anyone remember or know if they still are for sale ore if anyone still have 4 of'emGrateful if someone has info about this

[Chryco Psycho]

Often the heads were threaded / knurled , this tightened the guide so it could be machined back into spec , the knurling helps to trap oil for lubrication also , This is not an insert .