What is the dimension from the front of receiver to the pin hole?

The one I bought is 12 inches overall length (49120), with the center of the pin-hole being 2-1/2 inches back from the front of the receiver. I hope that helps.

Could I drill this to make it a short receiver extension? If so, what type of bit would be needed for this metal?

It is not hard metal, & can be cut & drilled with standard mettle bits & saws. The standard hitch goes all the way to the back of this short receiver. I can not imagine of any application for a 2" hitch would want it any shorter. I welded one on each side of an excavator bucket, put a 4'- 2"x2" steel in each one with wood planks across them to turn an excavator into a fork lift to shingle a roof.

What is the inside dimension?

I'm not sure of the exact I.D. but it is the same as a 2" reciever you would have on your truck. any accesory made for a 2" hitch would slide into it

Do these fit class 4 ball mounts or just class 3 ball mounts?

That depends on the structural integrity of the framing and welding to mount it on the vehicle. I'm sure that the piece itself can handle Class 4 loads (up to 10K lb.) If you can get a Class 4 ball on a 2" square bar that will plug into this, and your welding/framing is good, seems like it should be ok. But I'd suggest consulting a trailer hitch shop to be sure.

ASIN	B001GMZH5E
Automotive Fit Type	Universal Fit
Best Sellers Rank	#102,748 in Automotive ( See Top 100 in Automotive ) #139 in Automotive Hitch Receivers
Brand	CURT
Brand Name	CURT
Compatible with Vehicle Type	Trailer
Country of Publication	USA
Customer Reviews	4.7 out of 5 stars 1,673 Reviews
Finish Type	Polished
Finish type	Polished
Global Trade Identification Number	00612314509003
Included Components	Raw Receiver Tubing
Item Type Name	2-Inch x 6-Inch Weld-On Raw Steel Trailer Hitch Receiver Tube
Item Weight	1.51 Kilograms
Item weight	1.51 Kilograms
Manufacturer	Curt Manufacturing
Manufacturer Part Number	49060
Manufacturer Warranty Description	Limited Lifetime Warranty (One-Year Finish, One-Year Parts)
Material	Alloy Steel
Material Type	Alloy Steel
Model Number	49060
OEM Equivalent Part Number	49060
Pull Force	3500 Pounds
Pull force	3500 Pounds
UPC	612314509003
Unit Count	1.0 Count
Vehicle service type	Trailer

CURT 49060 2-Inch x 6-Inch Weld-On Raw Steel Trailer Hitch Receiver Tube

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