Rebuild kit question

[Skman]

I went onto Quickserv to see which kit I would need to do inframe. But it's telling me there is an option for 150 and 152 liners. I figured Quickserv would know by my ESN which one I would need but I guess not.
So I called Kenworth and asked the parts guy how I could tell which one I need and he says "you gotta measure it!!"
So, I said well...I'd kinda like to know which one before I start tearing anything down....just in case they're backordered for months.
He says "yeah I suppose that makes sense...but you'll have to call back when other guys are in. They might know how to figure it out"
Figured I'd come on here and see if there's a way to know WITHOUT tearing apart the engine?
Thanks