how old is it???

[bob]

i have a 27 year old mobile home furnace i just bought..i want to know if this is the original one or has it been replaced....i need to know how old it is.?.here is all the info i got off it. I want to know if the original could have been replaced and this one is not 27 years old like the trailer? Also, I cant find B.T.U’s anywhere..can you tell me what that is? Thanks so very much….

Beckett Burner
RWB # X-636513 Model # AF15
Pump
Single Stage Webster 3450 rpm
Motor
Mfg. # L853 Emerson Motor Div. 1/7h.p. So55GYJTK-5181

On Door it says Miller Home
On the plate it says: Lear Siegler Inc. Holland Michigan No. J-817219 103286000
Ser.# 150120 102743000

It also says: MOC-80-1 on the plate