The value can vary widely based on condition and age. A Colt DA 38 can sell anywhere between $300-1,000.
No way to value without a detailed description
10-1000 USD or so
The Colt DA 38 Model # 1901, can only use a 38 short, not a long or special.
Impossible to value with just the sn.
Only Colt knows
Yes.
You could get a historical letter from Colt. Cost is about 100 USD or so.
DA 38 Seril # Army 138 501
What model?
No such Colt model
A type of DA revolver made by Colt.
You can call Colt and they will tell you when it was made. Value can't be given since you don't describe the condition, finish, grips, barrel length, box, accessories, papers, etc.