Clutch issues 65 C10

[mrdave03]

Hi All, I noticed over the weekend when releasing the clutch 65 C10 (3 on the tree) I hear a short squeal sound as clutch fully engages. I'm thinking possible throw out bearing. That being said. A few years ago the 230 inline 6 cyl was swapped for small block 327. I don't recall the guy who swapped touching clutch at all. Just bolted up to original bell housing. So... how do I tell if it is still a 10" clutch? Can I use either 10" or 11" no issues? I'm thinking as it looks like rear main seal may be weeping as there is oil droplets on the bell housing. That I might just swap clutch.. TO bearing..resurface flywheel..rear seal.. but want to have all parts in hand before pulling apart. There is less than 1000 miles on the truck since the 327 was rebuilt and installed as I have been too busy to run it much. Thanks!