Hi Steve,
I'll see if I can help. In this case pictures go a long way. Ever since about year 2000, Reese has kept the same HP trunnion hitch head part number but the head itself has changed.
You said the 3 pieces welded head. That is a good one, I have 3 of them and the all cast one that replaced it. But...Reese made so many trunnion bar heads I want to make sure your is not by chance one of the pre 2000 vintage ones.
This is the 3 piece head with the serrated washer tilt. Reese pn 58167
Here is the 1 piece all cast steel that replaced it.
The newer all cast steel 58167 has a higher boss for a ball mount to help hide the nut so the trunnion bar does not hit it and is of course all cast.
This all cast head was before the 58167. It had a square washer tilt adjust. Was popular pre2000 time frame but many may have been on dealer stock shelves way into the ~ 2003 maybe 2004 time frame.
As to the 58167 ratings, this is clear as mud.
The first one I bought in 2004, was a 3 piece welded, had no sticker. But in that time frame they never made a WD bar larger than 1,200#. Time went by, around ~ 2006 Reese came out with 1,700# bars and had to have a head to go with it. In 2007 I bought a new 3 piece and now it has a sticker on it. You can see the weld under the date.
I bought that head with my 1,700# WD bars and 2 1/2" shank. And Made in the USA. I'm keeping it for sure.
Then the all cast newer 58167 came on the seen and it has the same sticker
The sticker started showing up once Reese started making WD bars larger than 1,200#
If you can take some pics and post, I can usually spot what it is by the identifying features as to what vintage it is. Reese also has a 1-800 tech service hot line and they can tell you, may need to email them a pic too so they know exactly what you have
The HP DC... This too has now changed several times. Can you link or post a pic of the vintage you are looking at? They are all good, just some of the more recent ones have some oddity things about them to be heads up when mounting.
I myself have the 2004 vintage HP DC, the 1st redesign since the older standard Reese DC which mounted with U bolts. It is till going strong, has over 50,000 miles on it running heavy TW's. I have full faith I can get over 150K miles on it and maybe even more. However... there are some learning things on how to set them up so they do not bind in a turn and snap off the arm. The newer redesign helped the binding but has other concerns to again watch out for with the frame brackets bend radius.
Again, post or link a pic can help better
Hope this helps
John