Structure of Allyl Cation

Propane, Propene and Their Radical Cations. Part 5: The structure of allyl cation.
One mode of stabilization for the propene radical cation consists in loosing an H-radical to form allyl cation. The allyl cation is symmetric and contains two CC bonds of length 138.2 pm. How does that bond length compare to a C-C single and a C=C double bond?


Figure. The MP2(full)/6-31G* optimized structure of allyl cation.