From JD parts, you can check the parts lists for comparability.
No 7
https://partscatalog.deere.com/jdrc/navigation/equipment/12776/level/2/snp/MjIxOTE1OkNIQVBURVJbMTA2MTojQlVTSU5FU1NfUkVHSU9OLDY2NTY6I0NBVEFMT0csMTI3NzY6RVFVSVBNRU5UXQ%3D%3D
JD 51...
ELllanito
Welcome to TBN. You've found a great source of information.
And looks like Tx Jim helped some with identification of your planter.
Maybe you would tell us more about this planter, and about yourself. We'd be interested to know more. thanks
Welcome to TBN
Photo is good but is too close up to know just what part of this machine you/we are looking at.
Would suggest, since you are into this machine so far, that you get the service tech manual to assist in the future.
Have you been to JD parts and located that spring and its part...
Put up a photo of your controls, and figure the PTO lever will be obvious to one of our members and help solve the mystery.
2 stage clutch ??
https://forums.yesterdaystractors.com/threads/1520-john-deere-pto-wont-engage-with-engine-running.1766935/
No knowledge of something that might fit your search, but have you considered looking for a used tractor/FEL combo that would work for you, leaving you with just the 4520 to find it a new home ??
Aaron-G
Welcome to TBN
Do you already have the front weight bracket ??
If so, just learn what is needed and add weights as needed.
If not, start with getting the weight bracket. ;);)
Is this considered the JD snowplow blade ? Or something that is custom made ? Maybe referred to as a 6-way blade ?
Any photo's of what you have in mind?
You are thanked for posting this, and can add it to your experience. Happy it ended up well for you in the end. (y)
May very well reach others too on TBN
Kenduro
Good that you have options as to where to buy the part. Better than no options at all. ;) :)
And the JD dealer parts man is going to support his dealership and JD. ;)