If your local NAPA causes that much trouble, I suggest you get them online. I've only needed these bolts for my CJ-6, and they were 5/16" size. The CJ springs are really narrow (1.75") and I would guess that the FSJ springs would use 3/8" bolts.
I bought these - https://www.amazon.com/Rancho-RS8127...80M/ref=sr_1_6
and these https://www.amazon.com/Rancho-RS8128...3A/ref=sr_1_11
and threw the 3/8" bolts in the junk bin, IIRC.
eTrailer has them cheap, but maybe not much cheaper than the Rancho ones when you add shipping.
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination ATs, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
ECO Green: '15 FCA Jeep Cherokee KL Trailhawk