This can only be a max deal of 3 years.
Contract Limits
Except for any contract inherited in 2010, all contracts must be no longer than five years. Also, for a given salary, all contacts (extension, FA) have term limits (max years contract can be per the salary) as provided below.
Maximum Years
<= $1.4m, 2 years
$1.5m - $5.4m, 3 years
$5.5m - $7.9m, 4 years
>=$8m, 5 years (the overall limit)