gm motor/rod bearing

Hi I am new to this forum and I need  some help,I purchased a 1989 gmc sierra  from a friend,he told me that it was not the original engine and that he thinks the engine in the truck now is a 350 5.7L,it has a knock in it so dropped the oil pan and found that the bearings for the last coonecting rod were gone.The journal looks fine and is within specs 2.0 inches.I took the #3 position rod bearing out and mic'd it at .067 inches,it had the following id on it(BEARING INSERT) GM4 fllwd by the #5471139 fllw the #122A 01 fllwd by 013 OS,I checked with a gm dealer and they could not id this bearing insert. I am hoping that someone on this forum will be able to id  this part,is it stndrd or ovrsz, what does the .013 OS mean.I tried tracking the engine with the intake mnfld #14102182 and cylinder head #14101081 and that came back with engines between 88-94 but nothing for a bearing  at .013 OS,the only info I could get to on the block was the #627 which is on both sides of the block also the main bearing caps have the number (GM) F3951 stamped on them.Any help would be greatly appreciated,I bought this truck just to haul stuff to and from the house other than that it will seldom be used.  

Was it mic'd with a bearing mic?  

A micrometer  

A bearing mic has one end thats flat and one end thats rounded. The bearing has to be measured in the center not on the ends. The thickness you have is wrong even for a std bearing.  

if you have an inside mic or a dial bore gauge, you can measure the bearing while its installed in the rod and then measure the rod without the bearing in it, subtract the numbers and that is the bearing thickness...but you can't measure at the splits, they both (rod end and bearing) will be bigger there  

The mic I used is the recommened mic to check the bearing thickness,the bearing measured .067 on the ends and .068 at the center.I know it seems odd but this the number that I am getting,any suggetions you have is appreciated.PS I also used a vernier caliper with digital readout and the results were .059 on the end and .060 in the center,I havent seen or read any on info on using a vernier to take this measurement but since I have it, I used it and am including this info for feedback.Its just strange  that the bearing is clearly marked GM4 as well as the data that I supplied in my previous post but mo one seems to be  able to cross it.  

I only took off the oilpan and the bearing cap for number 3 and 4 journnals.  

The std rod brg should measure less than .0625 I believe. I will check my books when I get to work this morn.  

Ok thanks.  

Std rod brg thickness is .0624. What you may have is a bearing made for a rod that has the ID cut oversize. This happens when a rod wont come in to spec when resizing so the ID is just cut large[oversized]. That would make the brg thicker. Do you have a machineshop you can get to measure it?  

You are correct,I did go to a machine shop and they said that it is a standard bearing so I just went with what they said for the engine however I was  wrong about the specs for the number 4 journal the book calls for a rod journal diameter of 2.0988-2.0998 from 1988 to 1995 I measured 2.024 and 2.077 on the journal since all the other journals are within specs can I just use oversized bearings  between this connecting rod and journal, all I want to do is haul a few things from the house three miles roundtrip and later when I can,properly rebuild the engine.I did put a stndrd bearing on the part of journal that measures 2.077 and the play was very minimal,I tried a .010 bearing on the side of the journal that measures 2.024 and there was a gap between the bearing and the journal,so what oversized bearing from stndrd should I try for this journal diameter of 2.024.I know this is not the norm. but if it is possible any input would be appreciated.  

Is the 2.024/2.077 for the same rod or just on same rod journal? Sounds like it has spun a rod brg.Your talking about almost .075 between the std size and what you have now. A rod brg will not live on a crank like that and the rod will need to be resized ae well.  

The same journal,tried a clevite .030 brng on the the journal (2.024) and it compensated quite a bit for the play do you think that I should try a .050 and again thanks for your input.  

You need a crank kit or get your crankshaft turned.