Help me Please with a 71 to 69 change over

[Cyclone44]

Hi Everyone, I have a couple of questions about my 69 C10 it's a longbed 3 on the tree 6 cyl. Last year I bought a 71 shortbed for parts, It had a very rusted out bondo filled body but it had a rebuilt factory disk brake frontend Somebody had heated and dropped the springs, So I pulled the whole frontend out cross member and all, And put it in my 69, I put the 69,s springs in the 71 frontend and it's about a 1 1/2 lower then it was with the original frontend can anybody tell me why? also I have the rearend from the 71 and it's a 3:08 and the 69 is a 3:73 and need it for pulling.. Can I just change the axels and brake drums to make it 5 lug all away around? Thanks for any help. George