There apparently are some differnces, but they might be mostly strength (different torque ratings).

B310 Head bolts:

Short:
A12S PN 11056-H1000 (van)
A12S, A13, A14S, A15 PN 11056-H2301

Long:
A12S PN 11059-H5000 (van)
A12S, A13, A14S, A15 PN 11059-H5700

I think the "long" bolt is the center bolt.

I'm not sure the difference between the two part numbers for A12S (carbureted motor). Both are listed for B310s.

Here are the B110 head bolts:

A12 11506-H1000
A12 11056-18000
A12 GX 11056-H2301
A12 GX 11056-H2300

A12 11057-18000
A12 11057-H1000
A12 GX 11057-H2300
A12 GX 11057-H2301

They're each around $80 through Summit although the A14 set shows up as an L20 set. Wierd. Are th A14 and A12 head hardware different?

A12 is 202-4202

A14 is 202-4203

Marvellous
These appear to be head studs not bolts.
I'm looking for ARP head studs for mine.
Can you read the part # off the box for me please ?

Yes, ARP is probably the most famous bolt maker in the US hot rod aftermarket.

Excuse my ignorance, but, what is Arp? Seems like a known bolt maker, right? Probably a tip I should learn.
Jaime.____________________________

Thanks for the help finn!

Finn, that is a very impressive looking A15!

I have Arp cylider head bolts in my A15.

Here is picture of those:http://www.sunpoint.net/~finndatsun/arp.jpg

Arp bolts are really good, I have used 1.5 bar boost in my A15, Twin dellortos, Garret T25.

I have payen standard head gasget.

Here is picture of my engine:http://www.sunpoint.net/~finndatsun/a15t.jpg

Yes, they do. The search box should show up some links.