Sorry Bryan.
While there is no such thing as a stupid question, there are, occasionally, questions whose answer appear to be found in the questioner's query.
If you measured 38 inches and you don't indicate anything unusual about your axle, then the answer is - obviously - 38 inches.
So, a better question might be:
"I am not sure that my perches are OEM. They look like they were grinded off and moved. The distance between the centers (or the distance between the inside edges) of the perches are 38 inches and the width of the perch is "xx" inches. Is this correct?"
Filling in a few more details on the nature of your question is liable to cause the readers of posts (both here and elsewhere) to wonder what the actual answer is and go out in a driving snowstorm with a tape measure and find out for you.
I hope this helps!