Filing form 8453 because of too many transactions on 1099-B my question is do I ask for an extension or what should I do in this case.

[JohnH2]

You have the correct approach.  You can file Form 8453, Transmittal, with the Form 8949 box checked.  You can input the summary totals of long term and short term gains and losses into your return and e-file.  If you have more than 500 transactions in the on-line versions of TurboTax or more than 2,000 transactions in the Desktop versions, you can use an outside service to generate a Form 8949 for paper submission.  A link for this follows:  https://www.form8949.com/ 

You can also use the TurboTax Desktop versions in Forms mode, to generate a Form 8949.