The characters feel natural, which is good. I think the bolded comment below
“You’re young, smart, and, because I’m secure in my masculinity, a handsome dude”
feels a little artificial. I know speech isn’t always logical but as it stands this suggests that Cal is handsome because Frank is secure in his masculinity. I’d suggest:
“You’re young, smart…and I’m only saying this because I’m secure in my masculinity…you’re a handsome dude.”
Something along those lines?
I think you’ve captured the sense of place and character well. Some short stories tell you all you need to know, some make you want to know more. This falls in the latter for me. It’s almost like being a customer at the garage and overhearing this snippet.
I guess you’re mainly interested in dialogue but a quick look at a descriptive passage:
The sign above the door reads “Franks Garage” and consisted of only one large door and a small storage area in the back. He only works on classic cars and business was getting slower and slower.
I think the second instance of ‘door’ is a mistake. How about “…and the place consists of only one large work area” ?
The second sentence slips into present tense. “He only worked on classic cars…” seems more consistent to me. Although, going off my previous comment about how the story is like over-hearing, the entire scenario might actually work in present tense.
Thanks to Kevin for sorting out my technical issues with the comments here!
Spiderj: I don’t know. the “because I’m secure in my masculinity” was a break in his listing of attributes. You should be able to remove the break and the sentence will flow without it. If I remove yours it reads “You’re young, smart, you’re a handsome dude.” I guess I could break it into 2 sentences.
As for the ‘door’, it was suppose to be ‘a large garage door’ but the story as it appears above is exactly 1024 characters. :)
I’ll will see if I can tweak some things around though and see how it looks. Thanks for the info.
Jer Ray 
Kevin Lawver 
Spiderj