i have a 340 in my challenger. It looks like the hole where the dipstick tube goes in has a metal lining through the whole shaft and lips over the edge. At first i thought it was another dipstick tube that was broken off inside, but this is not the case. It looks factory and another block that i have is the same dealio. i cannot find a dipstick tube that is small enough in diameter to slide in. whats up with this?

I had that issue with a chrome mr gasket tube I was using as a quick fix. So much for that. Seems aftermarket stuffs don't all cut the mustard.

Got a stock replacement at NAPA and haven't looked back.

I'm sure you have the old dip stick tube broke off in the block. Try a good size easyout and it will come out so you can put in a new one. Good luck.

The hole size in the block for the dip stick tube is right around .368" ~.370".

Sounds like you are looking at the flare edge of the broken off tube. you will have to get this out of the block before you can even think about putting the new one in. You may have to sine up the new tube slightly to get to start into the hole when you do get the old broken end out.

Snapped a couple pictures of some blocks I have laying around, this is what it needs to look like to be ready for a new dip stick. The broken peice in the block with come out, is the motor in the car?