Dean (DAM16) is correct. A grade 3 Parker, regardless of gauge, year of mfg. or whether mfg. at Meriden CT., or Ilion NY, us a DH- or if the receiver has the front trip rods, a DHE- With the barrels absent, you can still get a reading on the frame size-aprox. although for some strange (to me anyway) reason, Parker stamped the frame size on the underside of the barrel lug, at the rear, near the tool steel wear plate-- But Frame size on Parkers is related to the center to center distance of the firing pin holes in the standing breech. A No. 1 frame size- 1" even span, the No. 0 size, is, I believe, 7/8"--

I would suggest you contact Larry Del Grego and Sons In upstate NY- you'll get better results there than from Remington-

"The field is the touchstone of the man"..