Those 42-47 truck open rears will most likely be 3.78. All the ones I've had, been that ratio. Look on the center housing there will be two sets of numbers stamped on the ridge running parallel to the pinion, divide those and it will give you the ratio. Provided no one has changed the ring and pinion.
If you like, I can take a picture of where the numbers are. I have one mocked up in my roadster right now. It has 3.78 and a T5 behind a hot flathead. I have a Camaro T5 that I swapped the top plate and tailshaft housing of a S10 T5 on to it so I could have a 2.95 first gear ratio.
If you have a pic handy that will make it easier lol. Both of mine have some pretty thick paint. Haven't had a chance to get out and look yet. Brought the T5 home. Not sure how many actual miles are on it, there are signs that someone has opened it up before so it may have been gone through at one time. Had a brand new clutch and pressure plate which of course I won't use. Anyway it feels nice and tight. I'll pop the top cover off at some point and see what it looks like inside.
It's the T's turn for some love... needs a bunch of stuff to get roadworthy again but I'm starting with the head gasket. This Best 509g should cope with the compression better than the random copper gasket I pulled out of a parts engine... lol In terms of What Else... somehow the crank pulley is broken, the oil pan is leaking because I tried to change the timing cover without disturbing the pan gasket, and I may be switching back to the A distributor with the Nu-Rex automatic advance. Also it has been sitting outside and the tires which were old when I got them 4 or 5 years ago didn't get any younger... I'm still planning to put the T-5 in it, but I'm working on building a Corvette into a commuter and I need that done before I sink a bunch of money into the T. With the T-5 in the T it will be "commutable" but really only in very good weather conditions, so it's second priority... or maybe third... I'd sure like to make some progress on the g***er coupe too. Should have this part done tomorrow, but somehow none of my parts engines have usable crank pulleys. I think I'm going to try to weld this one back together before I replace it. I can't determine if this pulley is cast or a forging but at worst it will just still be broken so I'm just gonna give it a shot.
It's kinda spendy but I can't reccomend the machined pulley Charlie Yapp makes enough. He makes them in any size you want. I had lots of issues with various 1pc and 2pc pulleys (probably 4 total)wobbling and leaking real bad. Installed the yapp pulley and the leak stopped.
There ya go. Just load it up and pull that band aid off one time quickly lol. Hopefully you’ll forgot about the bill by the time the parts show up and it’ll be like Christmas
Sidecovers/pulleys/ waterpump adaptors are definitely the best things he offers. When I last ordered stuff he made it sound like he was winding down operations. Take that as you will. I dig your build I've been following along for awhile now you definitely got me motivated on my RPU.
The Jalopy Journal
