Hi Doug and welcome,
Not wanting rain on anyone's parade but your truck is a 70 series not a 40 series.
If you post a photo of the vin plate (should be on the bulkhead) we'll be able to tell you exactly what you have which, of course, will potentially help in getting the right parts for it.
70 series are very good and strong trucks, to the point that they are still in production today, so actually that might make things easier for getting parts.
My apologies for being the bringer of this news, but rest assured, there are probably more 70 series owners on here than there are 40 series.
Regards,
Rodger