51L38-1-1AA is the hasp version in steel cadmium plating
The distance between the holes = 0.562 inch = 14,27mm
the hasp has a diameter of 0.34 inch = 8,6mm
It means your customer needs an alternative hasp version:
The following alternative exists:
https://www.latchlock.eu/MLLAY42Z however has a hole distance of 12,7mm , furthermore the hole of the hasp is also only 6mm
we do have stock available of the stainless steel variant: https://www.latchlock.eu/MLLAY42S
please check with the customer if this is acceptable
another alternative:
this comes without holes and is intended to be welded. However this has the advantage that the customer himself can drill the holes at the desired dimension. He will though then damage the plating at those spots.
As for the part number:
51L37-1-1AB
This is more complicated as it has an extended drawhook.
My advise though here would be for the customer to buy a standard latch,
With the same height: 0.62 inch = 15,7mm and same distance between the holes of 0.562 inch = 14,3mm; which would be version:
https://www.latchlock.eu/MLLA36Z or take the stainless steel version (preferred: https://www.latchlock.eu/MLLA36S )
the issue would be to machine shop the special drawhook.
We have that capability but need a detailed drawing or a sample of the special drawhook.
This will be costy though.