Thanks for the props Mark!
I've been doing tow rig setups for many years, I actually owned a wholesale/retail towing products operation mainly servicing new motor vehicle and rv/marine dealer accounts with full tow packages installed on their customer vehicles (new and used). I also had a business that was involved in moving deep-keel sailboats on an adjustable bunk trailer with a telescoping tongue so we could self-load and launch on steep angle boat ramps without having to hire a crane. Lake levels in texas can vary +/- 15 ft. Or more throughout a season and we needed to be able to pull boats on short notice when the flood season was on (and the droughts!).
So the equalizer system you were gifted is a welded unit. Those were the norm up through the early 80's. Then reese and others intro'd the adjustable head system so that as tow rigs were traded around, and trailers were traded around, a new head did not have to be sourced for each setup. And welded equalizer heads had to be welded up by a certified welder if you were doing this stuff in commercial trade.
That meant that the "properly" loaded trailer had to be leveled and measured out for estimating ball height, and then that height transferred to the tow rig which also had to be properly loaded with the family unit and all other items so that the ball height could be set and then the stinger/equalizer head welded up. Of course, the ball height also had to take into consideration how much lift the equalizer spring bars would lift the rear and lower the front when set for the loaded gross trailer weight. One hell of a lotta trouble!!!
The adjustable equalizer head development changed all that. Now we had a unit that was usable on any trailer/tow vehicle configuration (within reason) and only took maybe an hour to set up the first time.
So...in my opinion...you would be much better off in investing in an adjustable stinger/equalizer head that matches your style spring bars and snap-up brackets. All of the heads/spring bars interchange as long as ya stay with the same design.
That means...if your existing setup has "round" bars, then ya need a round bar head. If yours are "square" bars, then ya need a "trunnion" style head. Ya can't mix and match bars and heads!
The difference in the weight equalizing capacity of these systems is in the spring bars themselves. The receiver, the stinger, the head all are the same, but the bars (for a class iii) receiver setup) are rated in either 500, 750, or 1,000lb. Specs. A 1250lb. Spring bar set is for a class iv or v receiver.
With an adjustable head, you are set for life no matter what tow rig or trailer combo you are trying to hook up. Simply move the head up or down as needed or flip the stinger over to provide an even greater range of adjustment.
The adjustable heads all have a provision for setting the ball inclination which is measured from the horizontal surface/level. Again, with the tow rig sitting loaded and level with the trailer connected and the spring bars set, you want to incline the ball to the rear about 5*>8* from vertical. That provides for plenty of coupler articulation as the tow rig and trailer move up and down when in motion, and most especially when crabbing across a dip in the road, a driveway transition to a street, and "high centers". If the coupler should make hard contact with the equalizer head in any direction, it's almost guaranteed that the coupler will be forced off the ball and the safety chains then become the coupler!
If you can't quite make the equalizer head land where it needs to be to achieve nice ball height, then ya use a "riser" ball that provides either 1" or 2" of additional ball height, these are not spacers, but balls that are designed for this purpose. Some folks refer to those as "gooseneck" balls since they are popular for use in recessed pin boxes used on flatbed tow rigs pulling a true gooseneck or neck-over trailer (not a fifth wheel). A riser ball greatly increases the clearance between the outer edges of the trailer coupler and the equalizer head so that it's near impossible for a bottom-out to occur.
If you need pics explaining all this, I can take some tomorrow and post. I've also just completed the final setup of all this stuff on the chunk t'all. The fresh d60 axle goes back under on Monday and then we'll be able to use the rig to pull the trailer over to la pine for the annual IHSTO camporee, then down to norcal for the Sierra Fall Rallye, we take the mountain route/backroads for that excursion.
For examples of all this stuff, I use this site quite often:
http://www.etrailer.com/
