In my past experiences,,its usually abt. 4- 5 years,,especially on the old stuff.
What the d.m.v. lady told me at Concord d.m.v. office is that they usually have new employees go thru the computer and "purge" the system of all stuff with zero activity for the last 4-5 years,,especially older vehicles.
Thats why its so important to at least do a non-op on your old truck or car. Once its been deleted,as far as d.m.v. is concerned,,the vehicle never existed and you have to go thru a verification,trim their toe nails for them,give them a ride to work,lick their a$$,and pretty much just bend over and ask them,"please dont stick it in too far"(along with giving them a blank check and letting them fill in the amount)
Marty