Should I use this con rod? (was: part nrs on MkIII conrods)

I posted earlier asking questions about Command con rods - I seized a wristpin and holed a piston on my Mk III and I'm in the process of rebuilding.

After reading the various comments, I grabbed a rod from eBay - it was advertised as "I bought it some years ago as a spare - never installed or spun" - and it looks that way. The rod I bought says "23258 R1R1R" - my MkIII rod says "NM23258 R5R2R".

The R1R1R rod isn't at all identical to my MkIII rod, though the main dimensions are identical. Aside from not being shot peened and not having the 2 big end oil holes, the casting shape is quite different. The weights are also different, but very close - The old rod (R1R1R - no cap and nuts) weighs 9.1 oz - the MkIII rod weighs 9.5 oz. The old R1R1R cap weighs 5.4 oz - the MkIII cap weighs 5.3 oz. So I could match the weights & balance pretty easily without too much trouble.

So - does anybody want to weigh in on this? Should I use it, or keep looking for a newer rod that better matches mine?

Given that the rods look different the weight distribution might also be different , I would be inclined to try to source a couple of matched second hand rods.

I think the rods without the oiling hole in the big ends were pre-Commando, although they may also have been used on the first Commando 750s.

I'd agree with Dave, I once used a couple of the Atlas type rods by drilling the oiling hole that my Commando had.

Trying to reduce the weight on one rod & cap to match the other is not only false economy, but could end upo being a VERY expensive effort.

I guess to make myself clearer i'd be happy to use two of the earlier rod and just drill the holes. I once did that and got great service, I think the quality might just be better. I'd also want something that matched as exactly as possible.

Yeah, I'm getting to thinking that I need to find a pair - I could chase after singles for awhile and get a collection of rods that almost match <g>...

That is frustrating as there are a number of very similar ones out there. Back when I was putting together a motor from an Atlas and the Commando I blew up there was little info available. I spotted the oil holes and thought they were a good idea. If I recall I had tossed one of my Commando rods though the case.
I would even worry a bit about ebay rods because some folks will use anything. Do you think a vendor might be able to match up a rod for you? I used to have about ten rods but I gave them all away.

If you buy a pair from e-bay or another source where the guy has obviously dismantled an engine, because he is also selling the other parts, there is a reasonable chance that you will get a matched set. If you really push the boat out and buy a set of Carillo rods they don't come with the oil holes in them and I gather there is some debate as to the necessity of these holes. When I bought some Carillo rods I drilled the holes myself by using an old upper shell bearing for a guide for the starting point.

Oh, I wish I could afford those Carillo rods and the shallow pistons now! I'm thinking this is going to be a straight rebuild - get all the bike resto work done, do some riding - sooner or later a spare engine will fall into my lap, and then I'll build up a nice custom one as a winter project. I'm not so much after more HP, but more smoothness would be really nice! I'll be looking for matched rods - the problem with looking for stock new rods to match my single rod is price - the price on new rods from the usual places is REALLY HIGH.