Description

GEHL 663 Parts Catalog – What You Get When You Stop Relying on Aftermarket Junk

If you’ve ever ordered a part by eyeballing a blurry aftermarket diagram and ended up with the wrong seal kit, you know the waste of time and money I’m talking about. That’s why this GEHL 663 Parts Catalog lands on my bench when I need the real thing. It’s 142 pages of factory-original exploded views, part numbers, and torque specs that match what came out of the crate. No third-party reprints, no guesswork – just the PDF that GEHL printed for their own dealers.

The introduction on page 2 gives you the full abbreviation list – AB, ASY, BHB, CS, DIA, all of them. You’ll also find the serial number breakdown printed right on page 1: model, year code, month, unit number, engine type. That matters because some components changed between S/N breaks – like the Steer Select Valve (thru S/N 4311 vs. S/N 4312 and up). Miss that distinction with a generic catalog and you’re bolting on the wrong valve.

I’ve seen too many DIY guys grab an aftermarket “service manual” that lists generic bolt torques. This parts catalog gives you the standard attaching hardware torque values printed on the inside back cover – Grade 5 cap screws, Grade A nuts, the works. Not a wish list, factory spec.

Engine and Powertrain: What This Parts Catalog Covers

The Power Train section breaks down the engine external components, fuel lines, air intake (turbo and natural), exhaust, radiator/coolers. Two transmission variants: 12000 Series for S/N 4307 and up, 18000 Series thru S/N 4306. If you’re ordering a rebuild kit for a 18000 trans and you have a later machine, you’ll waste cash. The catalog flags that with serial number ranges right in the group heading.

Axle sections include Power Brake/Master Cylinder Assembly, Planetary & Wheel Assembly, Brake Caliper Assembly, Outer Knuckle End Group, Differential Carrier Group. Page 2 lists all abbreviations so you know what “DIA” means in the parts list. No head-scratching.

Does It Include Hydraulic Component Breakdowns?

Yes, and it’s detailed. The Hydraulic Components section covers every cylinder – Steer, Frame Level, Boom Lift, Boom Extend, Boom Slave, Attachment Tilt, Fork Shift, Rotate Carriage, Swing Carriage. Plus the Hydraulic Pump, Steer Select Valves (two S/N breaks), Joysticks, Priority Flow Divider, Flow Divider, Dual Relief Valve (two S/N breaks).

If you’ve ever replaced a joystick relief valve based on a parts counter guy’s guess, then had the machine drift, you’ll appreciate having the exact GEHL part number in front of you. The catalog also shows the hydraulic plumbing lines for the winch, steering, boom extend/lift, and carrier tilt/slave/auxiliary. No generic hose routing – OEM routing that matches your machine’s S/N.

3 Reasons to Stick with OEM Parts Documentation

First, part numbers are verified against GEHL’s production line. Second, the exploded views show how components nest together – that matters when you’re ordering a set of seals for the Boom Lift Cylinder and need to know if the guide ring comes with the piston or not. Third, torque specs are included for standard hardware (Grade 5 cap screws, hex nuts) so you don’t under- or over-tighten something that could cause a hydraulic leak at 3000 PSI. Aftermarket catalogs skip these details because they copy from memory, not from factory plates.

For those who want to pair this with the operation and maintenance side, check out the GEHL 663 Operators Manual – Factory Specs & Schematics for daily inspection and fluid capacities. If you own other GEHL machines from the same era, the GEHL SL4640, SL4840, SL5640, SL6640 2005 Parts Catalog and GEHL SL7610, SL7710, SL7810 2005 Parts Catalog – OEM Factory Specs follow the same format.

For background on the diesel engines used in this machine, read this Wikipedia article on diesel engines. It’s not a substitute for the catalog, but it explains the fundamentals of the turbo vs. natural intake systems referenced in the Powertrain section.

Get the Part Number Right the First Time

One of the biggest time-wasters in a home garage is ordering the wrong part because the diagram showed 12 bolts when your machine only has 10. The GEHL 663 Parts Catalog gives you serial-number-specific groups. Example: the Cab Group without optional A/C is split into part 1 and part 2 – each with its own component list. The Numerical Index at the back lets you cross-reference any part number back to its group page. No flipping through random sections.

Standard attaching hardware like cotter pins, set screws, woodruff keys, and nuts are indented under the part they belong to in the parts list. That means when you order a boom lift cylinder, you know which retaining ring and pin come with it. Not separate – included.

What You Won’t Find in Aftermarket Copies

Every aftermarket “parts manual” I’ve seen for compact telescopic handlers omits the decal locations. This OEM catalog dedicates four separate groups to decal locations – Frame and Chassis, Operator’s Station, Frame and Boom (two different S/N ranges). Why does that matter? Because safety decals are a legal requirement for the operator. If you strip them off during a repaint and don’t know where they go, you’re exposing yourself and anyone who borrows the machine to liability. The catalog shows exact placement.

Also, the Autotroll section (Electrical, Hydraulic Plumbing, Boom Components) is absent from any generic version I’ve ever cross-referenced. That’s a proprietary GEHL system – if you’re working on one, you need the factory document.

The PDF bookmarks mirror the TOC exactly – Introduction, Operator’s Station, Chassis/Covers/Tanks, Powertrain, Axles, Boom Components, Hydraulic Systems, Hydraulic Components, Autotroll, Numerical Index, Torque Specifications. Each section is clickable for instant navigation.

Does this catalog cover the GEHL 663 operator’s station interior?

Yes – dash, steering column, floor area, lights, and cab groups (with or without A/C) are broken out.

What serial number breaks are included?

The manual covers multiple S/N ranges – 4307 and up, thru 4306, 4307-4314 and up, etc. Specific components like the Steer Select Valve list two S/N breaks: thru 4311 and 4312 and up.

Are torque specifications printed for every fastener?

Standard attaching hardware torque values are provided on the inside back cover (Grade 5 cap screws, Grade A nuts). For hydraulic component-specific torques – like the Dual Relief Valve or Joystick Relief Valve – you need to reference the individual cylinder or valve group pages. The catalog does not list torques for every single bolt individually; it follows GEHL’s practice of providing standard values plus special torques where needed. For example, the steer cylinder probably uses standard cap screw torque unless noted otherwise in the group page.

Can I use this catalog to rebuild the transmission?

It lists parts for the 12000 and 18000 series transmissions, but it is a parts catalog, not a service manual. You will get the correct bearing and seal part numbers, but for step-by-step rebuild procedures you need the factory service manual. The this Wikipedia article on diesel engines can give you background on engine operation, but won’t replace the parts catalog.

Access the Factory Manual and keep it on your tablet or print the sections you need. Every part number is verified against GEHL’s original release. No reprints, no copies – just the 142-page PDF that the manufacturer intended for their dealers. You’ll save yourself one trip to the parts counter, minimum.