I just bought a Fontaine Top Plate for a peterbilt. A "6000" Series I believe. It was $1265 plus $200 shipped. But its lightweight, 200 lbs or so..... 2 Guys can pick it up and install.
Also... most of our hydro pumps are 27 Gal per minute. Some trailers or attachments (i.e. zachlift wrecker) will be more like 9 Gal per minute. Be careful because you will damage check valve and lines if you overburden the system. They do sell a metering block...... for like a Couple hundred bucks, that you can adjust to send say 18 gal. per minute back to the hydro tank before entering system. Its adjusted by a allen head. Good Luck