Buck Model 80

I think I have found a diamond in the rough for my son's house. He was looking for an insert for his fireplace and I found this Model 80 Buck . We went and looked at it and brought it home. It looks to be in very good condition. The owner said he bought it about 4 years ago and it worked great in his basement where he just moved from. Reason for selling was the house he moved to already has insert in fireplace. I have the manual for it and I noticed firebrick only on the bottom of the firebox and not on the sides. Do any of you know if it should have firebrick on the sides ? Here are a couple of pictures of it.

Got it with insulation blanket figured in on it also. That was going to be another question I was going to ask. I have an 8 inch on my 52 Bay and I think I could have got by with a 6 with the way it drafts on my 2 story house. My son's house is 2 story also and chimney alittle taller.