The 5 and 6 series are mainly of the older Ford design. I think there's one model in the 5 series (maybe 2) that are the Long tractor with the new name. The others are Ford types. The 675 has a Perkins engine and 665 and 675 both have Carraro from the clutch back. They have 12 speed fwd and rev Gear shuttle + flat platform.
Here's a copy and paste from the Farmtrac web site:
Farmtrac now offers replacement engines for most of the Ford
3000 and 4000 Series tractors originally equipped with 175,
192, or 201 cubic inch engines. If you own an older Ford tractor
that is in need of a complete engine overhaul, contact your
local Farmtrac dealer to learn more about our new, emission-
compliant replacement engines.
For just a little more than the cost of an overhaul on your
current engine, and for much less than replacing with an engine
purchased from New Holland, the Farmtrac Engine Kit features
the SAME reliable engine that comes on new Farmtrac tractors
today and that had been factory installed in the past on new
Ford tractors. Engine kit includes new fuel injection equipment,
water pump, fan belt pulley, starter and alternator.
Here's a link to Escorts afri:
Escorts agri..
And another:
Escort agri products..
Forgot to mention. Even with the perkins engine mine still uses Ford air filters and many other Ford parts. Just from my memory (and it isn't as good as it use to be) the Farmtrac looks a lot like a Ford tractor that was being sold in my area that came out of Canada in the 70's. They had the head lights in the grill and just looked a little different(fenders). Those tractors are still running today. They were sold at a lesser price than American Ford tractors then. Seemed to hold up just as well.
Back when I bought my Farmtrac 80 (now 675) my dealer told me they were made in India in the old Ford tractor plant. Said you could throw a rock over to the JD plant from it. He also said Escorts had bought the patent of the Ford tractors that were no longer being made.
LG at one time was in this deal too. Haven't kept up with the compact line so I won't comment on them. The 7 series is made by SAME for Farmtrac. I like the looks of those but a little to much $$$$$$ for me right now.