M13 X 25 Bolts

Your spec is open to misunderstanding. Is this a bolt (intended to be fastened with a nut) or a cap screw (intended to be fastened into a threaded hole)?

You seem to be asking for a 13 mm diameter, coarse thread. Is that right?

You seem to want this bolt to be 25 mm long. Is that right?

What sort of corrosion will it be exposed to?

Do you need to assemble/disassemble this?

Will it be subject to tightening to a torque spec?

Do you intend to use antiseize on this?

That's all I can think of at the moment.

does M13 Exist ? As far as my knowledge goes it is M14 after M12 (and that too with M14 being non-preferable size).

As far as the designation -

M12 x 1 x 25

M Means metric Thread 12mm outside diameter of the screw/bolt (just a bit less due to the tolerance of course) x1 means the thread pitch is 1mm x 25 means the length of the bolt (excluding head for socket and hex head and including head for counter-sunk type) is 25 mm.

in case the middle x1 is missing ie

M12 x 25 means metric Thread 12mm outside diameter of the screw/bolt (just a bit less due to the tolerance of course) standard (coarse pitch) , length of the bolt 25mm.

in your case of M13 x 25 the standard pitch for the M13 does not exist, so though the M13 is manufacturable as a special fastener, the pitch must be specified (which obviously can not be 25mm) it has to be somewhere in between 1.75mm (standard M12) and 2.00mm (standard M14)

UD15

Ya need to talk to SAAB about those M13's.

It could be possible that a bolt 1/2" x1" was replaced with a special bolt customized although not standard.

I met such CRAZY solutions which cost a BIG lot of money!

I general it is possible to take the nearest metric dimension and modify if needed the class.

In this case it would be the simplest solution for the OP to change to M12 10.9 or 12.9.

If he wants to stay with M13 then he has to copy the parts he already has.

That may be the answer! If someone only familiar with metric measured it, they might well have rounded off to M13 X 25. I did the same once with a metric screw, assuming it matched the other several dozen US standard screws on the motor; it didn't.