Horsebox Advice wanted!

[magquiqui]

Hi! I bought a HB505 last year, my first box, it's about 25 years old but in great condition. Ive had a new braking and lights system put in and it's solid as. Id love to upgrade to a hbx506 when i have the funds, i love that they are brighter and there is more light inside for the horse, however I've been advised that the 505s are a much better quality of box! Can I get opinions please?!?!

 

[Suechoccy]

505s have metal fittings, 506s have more plastic fittings. 505s have simple rugged rubber mudgards on metal framework which can be bent back to shape if you reverse into a gatepost, 506s have more extended rubbery mudguards so more of them to catch on stuff.
506s will have locking trailer heads (useful security), 505s you'll need a hitchlock.

On the older 505s you'll get to a point where you'll need to replace tyres, side panels and ramps (front and rear).
You can have windows retrofitted to your 505 if that's the only reason you like the 506.