Dipstick tube question

I picked up a dipstick and tube at the junkyard today from a 74 Slant Six Dart.

Tried to put it in my 71 Slant Six and the tube just will not go in past 1/4" or so into the block. Started making me think there was a broken off tube piece stuck in the hole but I don't see or feel anything with a screwdriver blade.

I know this is a small thing but I am kinda stumped. Is there a trick? The tube I pulled at the junkyard came out without a huge amount of effort.

Thanks

Brian