I know what M8 means, it's a metric thread bolt that is 8mm diameter.
I assume that 45 mean 45mm long. Is that overall, or from the under the head?
What does 1.25" mean? It means "one and a quarter inches" to me, but it's probably not what you mean. And what is its relevance?.
I understand "socket head" to mean that the head is a cylinder without a taper to the bolt diameter, ie a square shoulder. The socket is where the Allen key goes.
Does any part of the bolt have an unthreaded portion? I'm thinking of the bit where the shock bushing fits.
If I fully understand what you are looking for, I would be happy to have a look as well.