RAParts C670FI Overrunning PTO Coupler (1 1/8 in x 1 3/8 in) - Tractor

In this review the RAParts C670FI overrunning power take off coupler is assessed for owners of older Ford/New Holland tractors who need a reliable PTO connection. The bottom line: this replacement coupler is best for mechanics and hobby farmers who want to upgrade a 1 1/8 in PTO shaft to the more common 1 3/8 in standard while retaining 540 rpm operation. The reviewer found the part to be straightforward to fit on tractors with a pre-drilled attachment hole and appreciated that it includes the required 8mm x 50mm roll pin, making installation cleaner and faster.

Key Features

• Direct replacement: Designed as a one new replacement overrunning PTO coupler that fits Ford Tractor models 2N, 8N, 9N, NAA and Jubilee, so owners can restore PTO function without major modifications.
• Shaft size upgrade: Increases shaft diameter from 1 1/8 in to the 1 3/8 in standard, which helps connect modern implements that require the larger male spline.
• Dual spline ends: Internal diameter/female 1.125 in with 6 spline and external diameter/male 1.375 in with 6 spline, providing a secure mating with compatible PTO shafts.
• 540 rpm ready: Intended for use with 540 rpm PTO shafts, making it suitable for most common tractor PTO-driven implements.
• Includes roll pin: Supplied with the required 8mm x 50mm roll pin for attachment, reducing the need to source small hardware separately.
• Length and extension: Overall coupler length is 6 3/4 in and it increases shaft length by about 4 in, useful where reach is limited.

Who It's For

The C670FI coupler is aimed at owners and technicians working on vintage Ford/New Holland tractors (2N, 8N, 9N, NAA, Jubilee) who need a durable, aftermarket replacement PTO coupler and want to upgrade to a 1 3/8 in standard shaft size. It suits those who use 540 rpm implements and have a tractor with the hole pre-drilled for attachment.

It is not intended for tractors lacking the pre-drilled mounting hole or for unusual PTO speeds other than 540 rpm. Buyers who require factory OEM branding or specialized friction clutch behavior should consider OEM or model-specific alternatives.

Pros & Cons

Pros

• Straightforward compatibility with several classic Ford tractor models makes replacement fast and predictable.
• Upgrades shaft diameter from 1 1/8 in to 1 3/8 in, allowing connection to modern implements.
• Includes the 8mm x 50mm roll pin, which simplifies installation and reduces small-part sourcing.
• Robust overall length and added shaft reach help clear driveline geometry limitations.

Cons

• Aftermarket part may differ slightly from OEM finish or fit, so minor adjustments during installation can be necessary.
• Designed specifically for 540 rpm PTO shafts, so it is not suited to tractors with other PTO speed arrangements.

Specifications

Part number replacements	48A27, C670FI, C670F, 271148
Fits tractor models	Ford 2N, 8N, 9N, NAA, Jubilee
Female I.D.	1.125 in with 6 spline
Male O.D.	1.375 in with 6 spline
Overall length	6 3/4 in
Shaft length increase	Approximately 4 in
Includes	8mm x 50mm roll pin for attachment

Our Verdict

The RAParts C670FI coupler is a practical, cost-effective aftermarket replacement for older Ford/New Holland tractors that need a 1 1/8 in to 1 3/8 in upgrade for 540 rpm PTO use. Its included roll pin and clear fitment to classic models make it a good value for DIY mechanics and small-scale farmers, provided the tractor has the pre-drilled attachment hole.

Frequently Asked Questions

Will this fit my 8N tractor?
Yes, the coupler is listed to fit Ford 8N tractors and similar models when the tractor has a pre-drilled hole for attachment.

Is the roll pin included?
Yes, the part ships with the required 8mm x 50mm roll pin for securing the coupler.

Can this be used on non-540 rpm PTOs?
No, this coupler is intended for use with 540 rpm PTO shafts and is not specified for other PTO speeds.