Laundry room gate valves messed up

Im getting a new washer/dryer soon, so i decided shut my gate valves and disconnect hoses. The cold water valve was stuck but i got it closed..the hot water valve shuts..but drips, and i attached a photo. The valve looks odd, not the typical nut like the others ive seen. It seems big. Can I just loosen that and pull the body out, and can i just buy a new body to slip back in...id rather not repack since its pretty old. What would a plumber charge for replacing?

No to the body of gate valve innard change..... and good luck with a swap out. I'd call that a boiler valve and it has a stem and a washer inside.

Looks like your stem packing is leaking too. A drip is ok when off because these valves only get used a few times a decade, typically.

You can replace the washers, repack the stems and grease the parts before closing up. Maybe, if you can get in to work there in height.

There are much better choices for washer shutoff valves. Many of us prefer the single lever that shuts off both hot and cold. We can't really give you an estimate on cost to replace, plumber rates vary widely from place to place. However, this should be a very simple job and probably cost just the minimum charge. It is not a difficult DIY job if you can sweat a copper joint.

You will probably NEVER find a new valve with the same mechanism as yours, so you have to change, or repair if possible, the valve. HOW you change it will depend entirely on what kind of connection your valve has and the picture does not show enough to tell us that. You may have a "one piece" valve which requires that you cut a hole in the wall to change it, or a "two piece" one which will unscrew from its "stem". That is NOT a gate valve, it is an angle "globe" valve.

tighten the smaller nut a about a 1/4 turn, it is just leaking at the packing nut.