@atreio
If you convert 37xx to 34xx i think that you know how to downgrade FW.I cant know that you dont read post on this forum and search in Tutorial INDEX.
To downgrade your nuvi you only download FW 6.60 and rename it to gupdate.gcd and add in your nuvi in folder .System and restart nuvi.
I dont want to be rude,but please read and search in tutorial index you will learn a lot of useful thing about your nuvi.
p.s.
I read all your post and i think other user to,but you only whait and whait in one Thread and dont search and read other Thread where you can find all answer.
Caty and other user create tutorials for help not becouse they have a spare time.
So please when you next time write something like you write in previous post,i beg you search around the forum and you will see that all is already writen and i always help till today,but after that post i will go offline for some time,becouse you lift my preasure.
Lolly Over and Out!!!