ht20 & trencher attachment-something is missing?-whats wrong with this picture?

Ok...I am pretty excited...I bought a bolens ht20 with a trencher attachment....the guy I bought it from...only owned it for a short time...and never used the trencher....he thinks there is suppose to be a 10 hp engine on the trencher...but I think its missing the 540 reduction gear box that reduces the pto speed to 540 rpm to operate the trencher...but this is the first trencher I have seen for bolens...and I do not even know the brand or model number...but I have heard of a bulldog 360 attachment for bolens..ok...now I have a lot of questions...would this be a a bulldog 360 trencher?...are my suspicions correct that it is missing the 540 gearbox?...would anyone know who would have the 540 gearbox for sale?...any information would be great...I am in the dark about this trencher...thanks!!