Ok. Yep, those bolts were for the gear. It's been 3 years. I remember now I had to special order a 12 point socket that size as normally available are all 6 point.
And yes, that top "nut" that can't be removed without sliding the IP back a bit is on a stud. Don't remember but makes sense that the other two would be studs also.
The triangle flange picture was not of a DB2. It is a Standadyne and was posted just to show all Standadynes did not all have slots. I could not find a DB2-4814 that showed the holes. Will be calling the place where I bought it tomorrow and ask. Mine is round.
I have a theory. We'll see if it pans out tomorrow. Somebody in the higher up Uhaul knows about the OilBurner site and said they had to find a way that the timing could not be easily advanced or any oilburner that rented one would be under the hood as it is pretty weak with a large load.
Because they were buying a bunch, Standadyne agreed to make a plate with non-slotted holes to keep the modifiers outta there. Heck, if I was working for Uhaul I'd probably have suggested the same!
Sorry but this now sounds more wife’s tale than truth.(Not suggesting you made this up, just thinking you just got bad info. Or trying to remember as you state the IP was replaced some time ago, you are now wanting to revisit and solve your issue.)
Talking about bitting off your nose to spite your face. The issue you are having is likely related to IP timing. As the IP and injectors wear the timing changes. Uhaul would have insured the truck was out of time by 40,000-50,000 miles. With no way to fix that.
Even if they replaced IP’s that failed with new ones it is not likely the truck would be timed. Standyne put alignment marks on these pumps. But after seeing dozens of pics on this site and a few in person, when timed I have never seen them perfectly lined up. Meaning their pumps don’t come timed. If you put a rebuild with a locked adjustment plate yours would likely be even more off.
Oil burners who have a timing meter also know moving the pump out of time does not make the NA motor faster, pull harder, or accelerate faster. So maybe a small few who did not know that would have bothered to try. But put these on thousands of trucks???? Turning up the fuel rate however does add power. If they wanted to solve a issue putting specialty bolts on the covers to the adjuster could have helped.
Also going forward please post accurate pictures. We want to help you but when you send pictures of something different than what you have. Also not stating it is not a pic of your actual part is not being considerate of the time we all are taking out of our busy day to solve your problem. So can you please send pics of your actual truck so we can see it? Then of the actual IP inside your truck so we can see how it mounts? A picture tells a 1,000 words as they say.
The reason I say this sounds like a wife’s tale is the only Uhauls I have seen with a IDI where the small box trucks on a Ford pickup or van platform. They used a IH/Navistar engine based on Ford’s requirements/specs.(Not someone else’s, Ford production truck, not a IH production truck) In all the reading I have done current and past I never saw it mentioned Uhaul’s IP was locked in position on the Ford platform and could not be timed. (By Uhaul or by special request of Uhaul via Ford.) I asked for a pic of the truck and IP as I do not proclaim to be a Uhaul historian. 1) I want to see if yours is based on a Ford platform. Maybe it was a larger International 30ft platform. 2) See it so it is documented here for future members to benefit from. 3) See this for my own curiosity.
To your point maybe Uhaul did this aftermarket at a large cost to them. But struggling how that cost was cheaper than retiming them every 30,000 miles to see if 6-20 fleet trucks were off time. Also what a blunder as the timing on a NA IDI is negligible. Where as turning up the pump would make some HP and potentially hurt the truck Long term.
If your hunch is correct I personally would put a different plate on the pump if easy or buy a different IP so I could time my engine. IDIBronco and I both regularly share how important correct timing on these IDI’s is.
Looking forward to seeing your truck and IP!