John Deere 437D is knuckleboom loader mounted on a trailer. You can choose from 3 basic configurations in your shop:
Sawbuck, Delimber and Loader only.
With sawbuck you can cut trees to different sizes. With delimber you can remove tree branches from trees you cut down. It can be used for loading logs on trailer as well.
For better stability when handling the trees, you can lock it to the arm (red area shows up at locking point). Be sure to unlock it before touching anything with the tree.

John Deere 437D
Shop category: Excavators, Trailers
Price:  230000 $
Power:  280 HP
Max. speed:  3 kph
Configurations:
- Design
- Wheels
- Arm type (log grapple or fast coupler)
- Tinted windows
- Fast coupler auto tilt (yes or no)
- Beacon lights
- Body color
- Cab color
- Grapple color
- Tools color
- Rim color

Attachments for fast coupler configuration:

Log Grapples (Fixed or dangle)
Shop category: Excavator Tools
Price:  15000 $

Attachable delimber
Shop category: Forestry miscellaneous
Price:  25000 $
You can attach it to 437D with sawbuck configuration so you can control both.

Default controls:
Lock tree to the arm - IMPLEMENT_EXTRA (key B)
Toggle grapple rotation (manual or free) - TOGGLE_PIPE (key O)
Unfold stabilizers - LOWER_IMPLEMENT (key V)
Cut tree - IMPLEMENT_EXTRA2 (key X)
Unfold sawbuck - IMPLEMENT_EXTRA4 (key Z)
Show measure tool (sawbuck) - IMPLEMENT_EXTRA3 (key Y)
Delimber claws - AXIS_CRANE_TOOL3

Delimber info:
Put the tree into the delimber. Then close delimber's claws and run the tree throw delimber by moving/rotating your arm. When delimbed, you can cut tree to specified length by saw placed on the back of the delimber.

If you find any errors or issues, let me know in comment or to [email protected] and i will fix it in next version.