John Deere 640G Series III to 748G Series III specifications

Choose the G-III loading system and transmission together

Deere's G-III brochure identifies the 640G-III as a cable skidder and the 648G-III and 748G-III as grapple machines. That is a different loading-system choice, not a sequence of interchangeable trim levels. Decide whether the work needs cable collection or a grapple before comparing power and transport dimensions.

For grapple equipment, the publication separates a single-function arch that raises and lowers the grapple from a dual-arch arrangement that reaches out as well as lifting. The latter changes how the load is brought over the rear of the machine. A quoted grapple opening alone does not establish which arch movements the offered skidder can make.

The same brochure distinguishes a standard powershift arrangement from a torque-converter option for the 640G-III and 648G-III. It also makes the heavy-duty decking blade optional on the 648G-III and standard on the 748G-III. Identify those options before treating a neighbouring model's weight or driveline description as applicable.

For the 600-series G-III machines, Deere describes a cooling fan that draws air through the front and discharges it at the sides. Its hydraulic drive reverses to clear the screen. Check the cooling-door access and installed fan arrangement when assessing debris cleaning on these particular skidders.

The technical manual separates direct-drive and converter machines

Deere's TM1870 diagnostic manual covers G-III skidders through its stated serial boundary. Its general-specification section gives separate entries for a direct-drive 640G-III and a torque-converter 640G-III, with separate winch references. Keep the serial scope and transmission arrangement with the specification when discussing a test result or ordering the applicable service literature.

The manual's winch descriptions also distinguish the 4000 and 6000 series. Those identifiers matter alongside bare-drum or full-drum measurements: a line-speed or pulling-force entry is tied to its winch and measuring condition. Do not transfer a result from one drum configuration to another based only on the skidder's engine rating.

The G-III documents do not identify every older E, G or later H machine in this comparison as mechanically identical. The complete historical columns remain available for their own designations, while the researched G-III distinctions above apply only to the models named by those publications.