Hd5

HD5B - had one like that - for your own work on site will work IF 
Slow , underpowered at 48 HP for a 10' blade , even turned the blade would cause problems transporting on roads to any jobsite .
I converted mine to 2 - hyd cylinders mounted to bull nose rather than geometry shown 
With a PTO could work for other uses . 
Price - High - sold mine for 1/2 that many years back 
Replaced it with a FA FD5 with 6 way blade and 80 HP power shift 
My HD5G loader could push more material than the dozer could as less resistance from bucket than 10' blade 
Parts can be found - EXCEPT undercarriage - track is made of unobtainium new and almost any good ones used 

Edited by Coke-in-MN - 18 hours 57 minutes ago at 9:25am

Early HD7 had the 3-71 and HD5A machines made for farm use were repowered with the 3-71 by owners for field work . With the short track they also bob a lot when holding grade .  If one were to reduce blade width it would be a better machine , along with making power angle on blade using the present center as pivot - but a lot of work making those changes .
 I bought the HD5B after I sold my D6-9U Cat as that was a money pit - even though it was a hydraulic lift blade . No angle dozing and tilting blade was manual screws on frame . 
 Early models were single speed reverse , with 5 fwd . 
HD5G loader with a 2-71 is fine and I used mine for years digging basements, loading trucks , leveling lots , putting in roads and driveways . Dug a couple basements under houses that were blocked up as overall height was low enough to get under house and push out material for larger machine to move 
 In hard or compacted soil that blade will not dig in , in light material it will work but slow . Check pins and bushings along with sprocket wear , also if truck frame is straight .
 When I bought my 5B it had broken axle and blower was seized as water froze and cracked lobe from drain plug hole in blower was closed off